Thomson problem

The objective of the Thomson problem is to determine the minimum electrostatic potential energy configuration of N electrons constrained to the surface of a unit sphere that repel each other with a force given by Coulomb's law. The physicist J. J. Thomson posed the problem in 1904 ^[1] after proposing an atomic model, later called the plum pudding model, based on his knowledge of the existence of negatively charged electrons within neutrally-charged atoms.

Related problems include the study of the geometry of the minimum energy configuration and the study of the large N behavior of the minimum energy.

Mathematical statement

The electrostatic interaction energy occurring between each pair of electrons of equal charges (${\displaystyle e_{i}=e_{j}=e}$, with ${\displaystyle e}$ the elementary charge of an electron) is given by Coulomb's law,

${\displaystyle U_{ij}(N)={e_{i}e_{j} \over 4\pi \epsilon _{0}r_{ij}},}$

where ${\displaystyle \epsilon _{0}}$ is the electric constant and ${\displaystyle r_{ij}=|\mathbf {r} _{i}-\mathbf {r} _{j}|}$ is the distance between each pair of electrons located at points on the sphere defined by vectors ${\displaystyle \mathbf {r} _{i}}$ and ${\displaystyle \mathbf {r} _{j}}$, respectively.

Simplified units of ${\displaystyle e=1}$ and ${\displaystyle k_{e}=1/4\pi \epsilon _{0}=1}$ (the Coulomb constant) are used without loss of generality. Then,

${\displaystyle U_{ij}(N)={1 \over r_{ij}}.}$

The total electrostatic potential energy of each N-electron configuration may then be expressed as the sum of all pair-wise interaction energies

${\displaystyle U(N)=\sum _{i<j}{\frac {1}{r_{ij}}}.}$

The global minimization of ${\displaystyle U(N)}$ over all possible configurations of N distinct points is typically found by numerical minimization algorithms.

Thomson's problem is related to the 7th of the eighteen unsolved mathematics problems proposed by the mathematician Steve Smale — "Distribution of points on the 2-sphere". ^[2] The main difference is that in Smale's problem the function to minimise is not the electrostatic potential ${\displaystyle 1 \over r_{ij}}$ but a logarithmic potential given by ${\displaystyle -\log r_{ij}.}$ A second difference is that Smale's question is about the asymptotic behaviour of the total potential when the number N of points goes to infinity, not for concrete values of N.

Example

The solution of the Thomson problem for two electrons is obtained when both electrons are as far apart as possible on opposite sides of the origin, ${\displaystyle r_{ij}=2r=2}$, or

${\displaystyle U(2)={1 \over 2}.}$

Known exact solutions

Schematic geometric solutions of the mathematical Thomson Problem for up to N = 5 electrons.

Mathematically exact minimum energy configurations have been rigorously identified in only a handful of cases.

• For N = 1, the solution is trivial. The single electron may reside at any point on the surface of the unit sphere. The total energy of the configuration is defined as zero because the charge of the electron is subject to no electric field due to other sources of charge.

• For N = 2, the optimal configuration consists of electrons at antipodal points. This represents the first one-dimensional solution.

• For N = 3, electrons reside at the vertices of an equilateral triangle about any great circle. ^[3] The great circle is often considered to define an equator about the sphere and the two points perpendicular to the plane are often considered poles to aid in discussions about the electrostatic configurations of many-N electron solutions. Also, this represents the first two-dimensional solution.

• For N = 4, electrons reside at the vertices of a regular tetrahedron. Of interest, this represents the first three-dimensional solution.

• For N = 5, a mathematically rigorous computer-aided solution was reported in 2010 with electrons residing at vertices of a triangular dipyramid. ^[4] Of interest, it is impossible for any N solution with five or more electrons to exhibit global equidistance among all pairs of electrons.

• For N = 6, electrons reside at vertices of a regular octahedron. ^[5] The configuration may be imagined as four electrons residing at the corners of a square about the equator and the remaining two residing at the poles.

• For N = 12, electrons reside at the vertices of a regular icosahedron. ^[6]

Geometric solutions of the Thomson problem for N = 4, 6, and 12 electrons are Platonic solids whose faces are all congruent equilateral triangles. Numerical solutions for N = 8 and 20 are not the regular convex polyhedral configurations of the remaining two Platonic solids, the cube and dodecahedron respectively. ^[7]

Generalizations

One can also ask for ground states of particles interacting with arbitrary potentials. To be mathematically precise, let f be a decreasing real-valued function, and define the energy functional

$${\displaystyle \sum _{i<j}f(|x_{i}-x_{j}|).}$$

Traditionally, one considers ${\displaystyle f(x)=x^{-\alpha }}$ also known as Riesz ${\displaystyle \alpha }$-kernels. For integrable Riesz kernels see the 1972 work of Landkof. ^[8] For non-integrable Riesz kernels, the Poppy-seed bagel theorem holds, see the 2004 work of Hardin and Saff. ^[9] Notable cases include: ^[10]

• α = ∞, the Tammes problem (packing);
• α = 1, the Thomson problem;
• α = 0, to maximize the product of distances, latterly known as Whyte's problem;
• α = −1 : maximum average distance problem.

One may also consider configurations of N points on a sphere of higher dimension. See spherical design.

Solution algorithms

Several algorithms have been applied to this problem. The focus since the millennium has been on local optimization methods applied to the energy function, although random walks have made their appearance: ^[10]

• constrained global optimization (Altschuler et al. 1994),
• steepest descent (Claxton and Benson 1966, Erber and Hockney 1991),
• random walk (Weinrach et al. 1990),
• genetic algorithm (Morris et al. 1996)

While the objective is to minimize the global electrostatic potential energy of each N-electron case, several algorithmic starting cases are of interest.

Continuous spherical shell charge

The extreme upper energy limit of the Thomson Problem is given by ${\displaystyle N^{2}/2}$ for a continuous shell charge followed by N(N − 1)/2, the energy associated with a random distribution of N electrons. Significantly lower energy of a given N-electron solution of the Thomson Problem with one charge at its origin is readily obtained by ${\displaystyle U(N)+N}$, where ${\displaystyle U(N)}$ are solutions of the Thomson Problem.

The energy of a continuous spherical shell of charge distributed across its surface is given by

${\displaystyle U_{\text{shell}}(N)={\frac {N^{2}}{2}}}$

and is, in general, greater than the energy of every Thomson problem solution. Note: Here N is used as a continuous variable that represents the infinitely divisible charge, Q, distributed across the spherical shell. For example, a spherical shell of ${\displaystyle N=1}$ represents the uniform distribution of a single electron's charge, ${\displaystyle -e}$, across the entire shell.

Randomly distributed point charges

The expected global energy of a system of electrons distributed in a purely random manner across the surface of the sphere is given by

${\displaystyle U_{\text{rand}}(N)={\frac {N(N-1)}{2}}}$

and is, in general, greater than the energy of every Thomson problem solution.

Here, N is a discrete variable that counts the number of electrons in the system. As well, ${\displaystyle U_{\text{rand}}(N)<U_{\text{shell}}(N)}$.

Charge-centered distribution

For every Nth solution of the Thomson problem there is an ${\displaystyle (N+1)}$th configuration that includes an electron at the origin of the sphere whose energy is simply the addition of N to the energy of the Nth solution. That is, ^[11]

${\displaystyle U_{0}(N+1)=U_{\text{Thom}}(N)+N.}$

Thus, if ${\displaystyle U_{\text{Thom}}(N)}$ is known exactly, then ${\displaystyle U_{0}(N+1)}$ is known exactly.

In general, ${\displaystyle U_{0}(N+1)}$ is greater than ${\displaystyle U_{\text{Thom}}(N+1)}$, but is remarkably closer to each ${\displaystyle (N+1)}$th Thomson solution than ${\displaystyle U_{\text{shell}}(N+1)}$ and ${\displaystyle U_{\text{rand}}(N+1)}$. Therefore, the charge-centered distribution represents a smaller "energy gap" to cross to arrive at a solution of each Thomson problem than algorithms that begin with the other two charge configurations.

Relations to other scientific problems

The Thomson problem is a natural consequence of J. J. Thomson's plum pudding model in the absence of its uniform positive background charge. ^[12]

"No fact discovered about the atom can be trivial, nor fail to accelerate the progress of physical science, for the greater part of natural philosophy is the outcome of the structure and mechanism of the atom."

—Sir J. J. Thomson ^[13]

Though experimental evidence led to the abandonment of Thomson's plum pudding model as a complete atomic model, irregularities observed in numerical energy solutions of the Thomson problem have been found to correspond with electron shell-filling in naturally occurring atoms throughout the periodic table of elements. ^[14]

The Thomson problem also plays a role in the study of other physical models including multi-electron bubbles and the surface ordering of liquid metal drops confined in Paul traps.

The generalized Thomson problem arises, for example, in determining arrangements of protein subunits that comprise the shells of spherical viruses. The "particles" in this application are clusters of protein subunits arranged on a shell. Other realizations include regular arrangements of colloid particles in colloidosomes, proposed for encapsulation of active ingredients such as drugs, nutrients or living cells, fullerene patterns of carbon atoms, and VSEPR theory. An example with long-range logarithmic interactions is provided by Abrikosov vortices that form at low temperatures in a superconducting metal shell with a large monopole at its center.

Configurations of smallest known energy

In the following table^{[ citation needed ]}${\displaystyle N}$ is the number of points (charges) in a configuration, ${\displaystyle U_{\textrm {Thom}}}$ is the energy, the symmetry type is given in Schönflies notation (see Point groups in three dimensions), and ${\displaystyle r_{i}}$ are the positions of the charges. Most symmetry types require the vector sum of the positions (and thus the electric dipole moment) to be zero.

It is customary to also consider the polyhedron formed by the convex hull of the points. Thus, ${\displaystyle v_{i}}$ is the number of vertices where the given number of edges meet, ${\displaystyle e}$ is the total number of edges, ${\displaystyle f_{3}}$ is the number of triangular faces, ${\displaystyle f_{4}}$ is the number of quadrilateral faces, and ${\displaystyle \theta _{1}}$ is the smallest angle subtended by vectors associated with the nearest charge pair. Note that the edge lengths are generally not equal. Thus, except in the cases N = 2, 3, 4, 6, 12, and the geodesic polyhedra, the convex hull is only topologically equivalent to the figure listed in the last column. ^[15]

N	${\displaystyle U_{\textrm {Thom}}}$	Symmetry	${\displaystyle \left|\sum \mathbf {r} _{i}\right|}$	${\displaystyle v_{3}}$	${\displaystyle v_{4}}$	${\displaystyle v_{5}}$	${\displaystyle v_{6}}$	${\displaystyle v_{7}}$	${\displaystyle v_{8}}$	${\displaystyle e}$	${\displaystyle f_{3}}$	${\displaystyle f_{4}}$	${\displaystyle \theta _{1}}$	Equivalent polyhedron
2	0.500000000	${\displaystyle D_{\infty h}}$	0	–	–	–	–	–	–	1	–	–	180.000°	digon
3	1.732050808	${\displaystyle D_{3h}}$	0	–	–	–	–	–	–	3	2	–	120.000°	triangle
4	3.674234614	${\displaystyle T_{d}}$	0	4	0	0	0	0	0	6	4	0	109.471°	tetrahedron
5	6.474691495	${\displaystyle D_{3h}}$	0	2	3	0	0	0	0	9	6	0	90.000°	triangular dipyramid
6	9.985281374	${\displaystyle O_{h}}$	0	0	6	0	0	0	0	12	8	0	90.000°	octahedron
7	14.452977414	${\displaystyle D_{5h}}$	0	0	5	2	0	0	0	15	10	0	72.000°	pentagonal dipyramid
8	19.675287861	${\displaystyle D_{4d}}$	0	0	8	0	0	0	0	16	8	2	71.694°	square antiprism
9	25.759986531	${\displaystyle D_{3h}}$	0	0	3	6	0	0	0	21	14	0	69.190°	triaugmented triangular prism
10	32.716949460	${\displaystyle D_{4d}}$	0	0	2	8	0	0	0	24	16	0	64.996°	gyroelongated square dipyramid
11	40.596450510	${\displaystyle C_{2v}}$	0.013219635	0	2	8	1	0	0	27	18	0	58.540°	edge-contracted icosahedron
12	49.165253058	${\displaystyle I_{h}}$	0	0	0	12	0	0	0	30	20	0	63.435°	icosahedron (geodesic sphere {3,5+}1,0)
13	58.853230612	${\displaystyle C_{2v}}$	0.008820367	0	1	10	2	0	0	33	22	0	52.317°
14	69.306363297	${\displaystyle D_{6d}}$	0	0	0	12	2	0	0	36	24	0	52.866°	gyroelongated hexagonal dipyramid
15	80.670244114	${\displaystyle D_{3}}$	0	0	0	12	3	0	0	39	26	0	49.225°
16	92.911655302	${\displaystyle T}$	0	0	0	12	4	0	0	42	28	0	48.936°	tetrahedrally diminished dodecahedron
17	106.050404829	${\displaystyle D_{5h}}$	0	0	0	12	5	0	0	45	30	0	50.108°	double-gyroelongated pentagonal dipyramid
18	120.084467447	${\displaystyle D_{4d}}$	0	0	2	8	8	0	0	48	32	0	47.534°
19	135.089467557	${\displaystyle C_{2v}}$	0.000135163	0	0	14	5	0	0	50	32	1	44.910°
20	150.881568334	${\displaystyle D_{3h}}$	0	0	0	12	8	0	0	54	36	0	46.093°
21	167.641622399	${\displaystyle C_{2v}}$	0.001406124	0	1	10	10	0	0	57	38	0	44.321°
22	185.287536149	${\displaystyle T_{d}}$	0	0	0	12	10	0	0	60	40	0	43.302°
23	203.930190663	${\displaystyle D_{3}}$	0	0	0	12	11	0	0	63	42	0	41.481°
24	223.347074052	${\displaystyle O}$	0	0	0	24	0	0	0	60	32	6	42.065°	snub cube
25	243.812760299	${\displaystyle C_{s}}$	0.001021305	0	0	14	11	0	0	68	44	1	39.610°
26	265.133326317	${\displaystyle C_{2}}$	0.001919065	0	0	12	14	0	0	72	48	0	38.842°
27	287.302615033	${\displaystyle D_{5h}}$	0	0	0	12	15	0	0	75	50	0	39.940°
28	310.491542358	${\displaystyle T}$	0	0	0	12	16	0	0	78	52	0	37.824°
29	334.634439920	${\displaystyle D_{3}}$	0	0	0	12	17	0	0	81	54	0	36.391°
30	359.603945904	${\displaystyle D_{2}}$	0	0	0	12	18	0	0	84	56	0	36.942°
31	385.530838063	${\displaystyle C_{3v}}$	0.003204712	0	0	12	19	0	0	87	58	0	36.373°
32	412.261274651	${\displaystyle I_{h}}$	0	0	0	12	20	0	0	90	60	0	37.377°	pentakis dodecahedron (geodesic sphere {3,5+}1,1)
33	440.204057448	${\displaystyle C_{s}}$	0.004356481	0	0	15	17	1	0	92	60	1	33.700°
34	468.904853281	${\displaystyle D_{2}}$	0	0	0	12	22	0	0	96	64	0	33.273°
35	498.569872491	${\displaystyle C_{2}}$	0.000419208	0	0	12	23	0	0	99	66	0	33.100°
36	529.122408375	${\displaystyle D_{2}}$	0	0	0	12	24	0	0	102	68	0	33.229°
37	560.618887731	${\displaystyle D_{5h}}$	0	0	0	12	25	0	0	105	70	0	32.332°
38	593.038503566	${\displaystyle D_{6d}}$	0	0	0	12	26	0	0	108	72	0	33.236°
39	626.389009017	${\displaystyle D_{3h}}$	0	0	0	12	27	0	0	111	74	0	32.053°
40	660.675278835	${\displaystyle T_{d}}$	0	0	0	12	28	0	0	114	76	0	31.916°
41	695.916744342	${\displaystyle D_{3h}}$	0	0	0	12	29	0	0	117	78	0	31.528°
42	732.078107544	${\displaystyle D_{5h}}$	0	0	0	12	30	0	0	120	80	0	31.245°
43	769.190846459	${\displaystyle C_{2v}}$	0.000399668	0	0	12	31	0	0	123	82	0	30.867°
44	807.174263085	${\displaystyle O_{h}}$	0	0	0	24	20	0	0	120	72	6	31.258°
45	846.188401061	${\displaystyle D_{3}}$	0	0	0	12	33	0	0	129	86	0	30.207°
46	886.167113639	${\displaystyle T}$	0	0	0	12	34	0	0	132	88	0	29.790°
47	927.059270680	${\displaystyle C_{s}}$	0.002482914	0	0	14	33	0	0	134	88	1	28.787°
48	968.713455344	${\displaystyle O}$	0	0	0	24	24	0	0	132	80	6	29.690°
49	1011.557182654	${\displaystyle C_{3}}$	0.001529341	0	0	12	37	0	0	141	94	0	28.387°
50	1055.182314726	${\displaystyle D_{6d}}$	0	0	0	12	38	0	0	144	96	0	29.231°
51	1099.819290319	${\displaystyle D_{3}}$	0	0	0	12	39	0	0	147	98	0	28.165°
52	1145.418964319	${\displaystyle C_{3}}$	0.000457327	0	0	12	40	0	0	150	100	0	27.670°
53	1191.922290416	${\displaystyle C_{2v}}$	0.000278469	0	0	18	35	0	0	150	96	3	27.137°
54	1239.361474729	${\displaystyle C_{2}}$	0.000137870	0	0	12	42	0	0	156	104	0	27.030°
55	1287.772720783	${\displaystyle C_{2}}$	0.000391696	0	0	12	43	0	0	159	106	0	26.615°
56	1337.094945276	${\displaystyle D_{2}}$	0	0	0	12	44	0	0	162	108	0	26.683°
57	1387.383229253	${\displaystyle D_{3}}$	0	0	0	12	45	0	0	165	110	0	26.702°
58	1438.618250640	${\displaystyle D_{2}}$	0	0	0	12	46	0	0	168	112	0	26.155°
59	1490.773335279	${\displaystyle C_{2}}$	0.000154286	0	0	14	43	2	0	171	114	0	26.170°
60	1543.830400976	${\displaystyle D_{3}}$	0	0	0	12	48	0	0	174	116	0	25.958°
61	1597.941830199	${\displaystyle C_{1}}$	0.001091717	0	0	12	49	0	0	177	118	0	25.392°
62	1652.909409898	${\displaystyle D_{5}}$	0	0	0	12	50	0	0	180	120	0	25.880°
63	1708.879681503	${\displaystyle D_{3}}$	0	0	0	12	51	0	0	183	122	0	25.257°
64	1765.802577927	${\displaystyle D_{2}}$	0	0	0	12	52	0	0	186	124	0	24.920°
65	1823.667960264	${\displaystyle C_{2}}$	0.000399515	0	0	12	53	0	0	189	126	0	24.527°
66	1882.441525304	${\displaystyle C_{2}}$	0.000776245	0	0	12	54	0	0	192	128	0	24.765°
67	1942.122700406	${\displaystyle D_{5}}$	0	0	0	12	55	0	0	195	130	0	24.727°
68	2002.874701749	${\displaystyle D_{2}}$	0	0	0	12	56	0	0	198	132	0	24.433°
69	2064.533483235	${\displaystyle D_{3}}$	0	0	0	12	57	0	0	201	134	0	24.137°
70	2127.100901551	${\displaystyle D_{2d}}$	0	0	0	12	50	0	0	200	128	4	24.291°
71	2190.649906425	${\displaystyle C_{2}}$	0.001256769	0	0	14	55	2	0	207	138	0	23.803°
72	2255.001190975	${\displaystyle I}$	0	0	0	12	60	0	0	210	140	0	24.492°	geodesic sphere {3,5+}2,1
73	2320.633883745	${\displaystyle C_{2}}$	0.001572959	0	0	12	61	0	0	213	142	0	22.810°
74	2387.072981838	${\displaystyle C_{2}}$	0.000641539	0	0	12	62	0	0	216	144	0	22.966°
75	2454.369689040	${\displaystyle D_{3}}$	0	0	0	12	63	0	0	219	146	0	22.736°
76	2522.674871841	${\displaystyle C_{2}}$	0.000943474	0	0	12	64	0	0	222	148	0	22.886°
77	2591.850152354	${\displaystyle D_{5}}$	0	0	0	12	65	0	0	225	150	0	23.286°
78	2662.046474566	${\displaystyle T_{h}}$	0	0	0	12	66	0	0	228	152	0	23.426°
79	2733.248357479	${\displaystyle C_{s}}$	0.000702921	0	0	12	63	1	0	230	152	1	22.636°
80	2805.355875981	${\displaystyle D_{4d}}$	0	0	0	16	64	0	0	232	152	2	22.778°
81	2878.522829664	${\displaystyle C_{2}}$	0.000194289	0	0	12	69	0	0	237	158	0	21.892°
82	2952.569675286	${\displaystyle D_{2}}$	0	0	0	12	70	0	0	240	160	0	22.206°
83	3027.528488921	${\displaystyle C_{2}}$	0.000339815	0	0	14	67	2	0	243	162	0	21.646°
84	3103.465124431	${\displaystyle C_{2}}$	0.000401973	0	0	12	72	0	0	246	164	0	21.513°
85	3180.361442939	${\displaystyle C_{2}}$	0.000416581	0	0	12	73	0	0	249	166	0	21.498°
86	3258.211605713	${\displaystyle C_{2}}$	0.001378932	0	0	12	74	0	0	252	168	0	21.522°
87	3337.000750014	${\displaystyle C_{2}}$	0.000754863	0	0	12	75	0	0	255	170	0	21.456°
88	3416.720196758	${\displaystyle D_{2}}$	0	0	0	12	76	0	0	258	172	0	21.486°
89	3497.439018625	${\displaystyle C_{2}}$	0.000070891	0	0	12	77	0	0	261	174	0	21.182°
90	3579.091222723	${\displaystyle D_{3}}$	0	0	0	12	78	0	0	264	176	0	21.230°
91	3661.713699320	${\displaystyle C_{2}}$	0.000033221	0	0	12	79	0	0	267	178	0	21.105°
92	3745.291636241	${\displaystyle D_{2}}$	0	0	0	12	80	0	0	270	180	0	21.026°
93	3829.844338421	${\displaystyle C_{2}}$	0.000213246	0	0	12	81	0	0	273	182	0	20.751°
94	3915.309269620	${\displaystyle D_{2}}$	0	0	0	12	82	0	0	276	184	0	20.952°
95	4001.771675565	${\displaystyle C_{2}}$	0.000116638	0	0	12	83	0	0	279	186	0	20.711°
96	4089.154010060	${\displaystyle C_{2}}$	0.000036310	0	0	12	84	0	0	282	188	0	20.687°
97	4177.533599622	${\displaystyle C_{2}}$	0.000096437	0	0	12	85	0	0	285	190	0	20.450°
98	4266.822464156	${\displaystyle C_{2}}$	0.000112916	0	0	12	86	0	0	288	192	0	20.422°
99	4357.139163132	${\displaystyle C_{2}}$	0.000156508	0	0	12	87	0	0	291	194	0	20.284°
100	4448.350634331	${\displaystyle T}$	0	0	0	12	88	0	0	294	196	0	20.297°
101	4540.590051694	${\displaystyle D_{3}}$	0	0	0	12	89	0	0	297	198	0	20.011°
102	4633.736565899	${\displaystyle D_{3}}$	0	0	0	12	90	0	0	300	200	0	20.040°
103	4727.836616833	${\displaystyle C_{2}}$	0.000201245	0	0	12	91	0	0	303	202	0	19.907°
104	4822.876522746	${\displaystyle D_{6}}$	0	0	0	12	92	0	0	306	204	0	19.957°
105	4919.000637616	${\displaystyle D_{3}}$	0	0	0	12	93	0	0	309	206	0	19.842°
106	5015.984595705	${\displaystyle D_{2}}$	0	0	0	12	94	0	0	312	208	0	19.658°
107	5113.953547724	${\displaystyle C_{2}}$	0.000064137	0	0	12	95	0	0	315	210	0	19.327°
108	5212.813507831	${\displaystyle C_{2}}$	0.000432525	0	0	12	96	0	0	318	212	0	19.327°
109	5312.735079920	${\displaystyle C_{2}}$	0.000647299	0	0	14	93	2	0	321	214	0	19.103°
110	5413.549294192	${\displaystyle D_{6}}$	0	0	0	12	98	0	0	324	216	0	19.476°
111	5515.293214587	${\displaystyle D_{3}}$	0	0	0	12	99	0	0	327	218	0	19.255°
112	5618.044882327	${\displaystyle D_{5}}$	0	0	0	12	100	0	0	330	220	0	19.351°
113	5721.824978027	${\displaystyle D_{3}}$	0	0	0	12	101	0	0	333	222	0	18.978°
114	5826.521572163	${\displaystyle C_{2}}$	0.000149772	0	0	12	102	0	0	336	224	0	18.836°
115	5932.181285777	${\displaystyle C_{3}}$	0.000049972	0	0	12	103	0	0	339	226	0	18.458°
116	6038.815593579	${\displaystyle C_{2}}$	0.000259726	0	0	12	104	0	0	342	228	0	18.386°
117	6146.342446579	${\displaystyle C_{2}}$	0.000127609	0	0	12	105	0	0	345	230	0	18.566°
118	6254.877027790	${\displaystyle C_{2}}$	0.000332475	0	0	12	106	0	0	348	232	0	18.455°
119	6364.347317479	${\displaystyle C_{2}}$	0.000685590	0	0	12	107	0	0	351	234	0	18.336°
120	6474.756324980	${\displaystyle C_{s}}$	0.001373062	0	0	12	108	0	0	354	236	0	18.418°
121	6586.121949584	${\displaystyle C_{3}}$	0.000838863	0	0	12	109	0	0	357	238	0	18.199°
122	6698.374499261	${\displaystyle I_{h}}$	0	0	0	12	110	0	0	360	240	0	18.612°	geodesic sphere {3,5+}2,2
123	6811.827228174	${\displaystyle C_{2v}}$	0.001939754	0	0	14	107	2	0	363	242	0	17.840°
124	6926.169974193	${\displaystyle D_{2}}$	0	0	0	12	112	0	0	366	244	0	18.111°
125	7041.473264023	${\displaystyle C_{2}}$	0.000088274	0	0	12	113	0	0	369	246	0	17.867°
126	7157.669224867	${\displaystyle D_{4}}$	0	0	2	16	100	8	0	372	248	0	17.920°
127	7274.819504675	${\displaystyle D_{5}}$	0	0	0	12	115	0	0	375	250	0	17.877°
128	7393.007443068	${\displaystyle C_{2}}$	0.000054132	0	0	12	116	0	0	378	252	0	17.814°
129	7512.107319268	${\displaystyle C_{2}}$	0.000030099	0	0	12	117	0	0	381	254	0	17.743°
130	7632.167378912	${\displaystyle C_{2}}$	0.000025622	0	0	12	118	0	0	384	256	0	17.683°
131	7753.205166941	${\displaystyle C_{2}}$	0.000305133	0	0	12	119	0	0	387	258	0	17.511°
132	7875.045342797	${\displaystyle I}$	0	0	0	12	120	0	0	390	260	0	17.958°	geodesic sphere {3,5+}3,1
133	7998.179212898	${\displaystyle C_{3}}$	0.000591438	0	0	12	121	0	0	393	262	0	17.133°
134	8122.089721194	${\displaystyle C_{2}}$	0.000470268	0	0	12	122	0	0	396	264	0	17.214°
135	8246.909486992	${\displaystyle D_{3}}$	0	0	0	12	123	0	0	399	266	0	17.431°
136	8372.743302539	${\displaystyle T}$	0	0	0	12	124	0	0	402	268	0	17.485°
137	8499.534494782	${\displaystyle D_{5}}$	0	0	0	12	125	0	0	405	270	0	17.560°
138	8627.406389880	${\displaystyle C_{2}}$	0.000473576	0	0	12	126	0	0	408	272	0	16.924°
139	8756.227056057	${\displaystyle C_{2}}$	0.000404228	0	0	12	127	0	0	411	274	0	16.673°
140	8885.980609041	${\displaystyle C_{1}}$	0.000630351	0	0	13	126	1	0	414	276	0	16.773°
141	9016.615349190	${\displaystyle C_{2v}}$	0.000376365	0	0	14	126	0	1	417	278	0	16.962°
142	9148.271579993	${\displaystyle C_{2}}$	0.000550138	0	0	12	130	0	0	420	280	0	16.840°
143	9280.839851192	${\displaystyle C_{2}}$	0.000255449	0	0	12	131	0	0	423	282	0	16.782°
144	9414.371794460	${\displaystyle D_{2}}$	0	0	0	12	132	0	0	426	284	0	16.953°
145	9548.928837232	${\displaystyle C_{s}}$	0.000094938	0	0	12	133	0	0	429	286	0	16.841°
146	9684.381825575	${\displaystyle D_{2}}$	0	0	0	12	134	0	0	432	288	0	16.905°
147	9820.932378373	${\displaystyle C_{2}}$	0.000636651	0	0	12	135	0	0	435	290	0	16.458°
148	9958.406004270	${\displaystyle C_{2}}$	0.000203701	0	0	12	136	0	0	438	292	0	16.627°
149	10096.859907397	${\displaystyle C_{1}}$	0.000638186	0	0	14	133	2	0	441	294	0	16.344°
150	10236.196436701	${\displaystyle T}$	0	0	0	12	138	0	0	444	296	0	16.405°
151	10376.571469275	${\displaystyle C_{2}}$	0.000153836	0	0	12	139	0	0	447	298	0	16.163°
152	10517.867592878	${\displaystyle D_{2}}$	0	0	0	12	140	0	0	450	300	0	16.117°
153	10660.082748237	${\displaystyle D_{3}}$	0	0	0	12	141	0	0	453	302	0	16.390°
154	10803.372421141	${\displaystyle C_{2}}$	0.000735800	0	0	12	142	0	0	456	304	0	16.078°
155	10947.574692279	${\displaystyle C_{2}}$	0.000603670	0	0	12	143	0	0	459	306	0	15.990°
156	11092.798311456	${\displaystyle C_{2}}$	0.000508534	0	0	12	144	0	0	462	308	0	15.822°
157	11238.903041156	${\displaystyle C_{2}}$	0.000357679	0	0	12	145	0	0	465	310	0	15.948°
158	11385.990186197	${\displaystyle C_{2}}$	0.000921918	0	0	12	146	0	0	468	312	0	15.987°
159	11534.023960956	${\displaystyle C_{2}}$	0.000381457	0	0	12	147	0	0	471	314	0	15.960°
160	11683.054805549	${\displaystyle D_{2}}$	0	0	0	12	148	0	0	474	316	0	15.961°
161	11833.084739465	${\displaystyle C_{2}}$	0.000056447	0	0	12	149	0	0	477	318	0	15.810°
162	11984.050335814	${\displaystyle D_{3}}$	0	0	0	12	150	0	0	480	320	0	15.813°
163	12136.013053220	${\displaystyle C_{2}}$	0.000120798	0	0	12	151	0	0	483	322	0	15.675°
164	12288.930105320	${\displaystyle D_{2}}$	0	0	0	12	152	0	0	486	324	0	15.655°
165	12442.804451373	${\displaystyle C_{2}}$	0.000091119	0	0	12	153	0	0	489	326	0	15.651°
166	12597.649071323	${\displaystyle D_{2d}}$	0	0	0	16	146	4	0	492	328	0	15.607°
167	12753.469429750	${\displaystyle C_{2}}$	0.000097382	0	0	12	155	0	0	495	330	0	15.600°
168	12910.212672268	${\displaystyle D_{3}}$	0	0	0	12	156	0	0	498	332	0	15.655°
169	13068.006451127	${\displaystyle C_{s}}$	0.000068102	0	0	13	155	1	0	501	334	0	15.537°
170	13226.681078541	${\displaystyle D_{2d}}$	0	0	0	12	158	0	0	504	336	0	15.569°
171	13386.355930717	${\displaystyle D_{3}}$	0	0	0	12	159	0	0	507	338	0	15.497°
172	13547.018108787	${\displaystyle C_{2v}}$	0.000547291	0	0	14	156	2	0	510	340	0	15.292°
173	13708.635243034	${\displaystyle C_{s}}$	0.000286544	0	0	12	161	0	0	513	342	0	15.225°
174	13871.187092292	${\displaystyle D_{2}}$	0	0	0	12	162	0	0	516	344	0	15.366°
175	14034.781306929	${\displaystyle C_{2}}$	0.000026686	0	0	12	163	0	0	519	346	0	15.252°
176	14199.354775632	${\displaystyle C_{1}}$	0.000283978	0	0	12	164	0	0	522	348	0	15.101°
177	14364.837545298	${\displaystyle D_{5}}$	0	0	0	12	165	0	0	525	350	0	15.269°
178	14531.309552587	${\displaystyle D_{2}}$	0	0	0	12	166	0	0	528	352	0	15.145°
179	14698.754594220	${\displaystyle C_{1}}$	0.000125113	0	0	13	165	1	0	531	354	0	14.968°
180	14867.099927525	${\displaystyle D_{2}}$	0	0	0	12	168	0	0	534	356	0	15.067°
181	15036.467239769	${\displaystyle C_{2}}$	0.000304193	0	0	12	169	0	0	537	358	0	15.002°
182	15206.730610906	${\displaystyle D_{5}}$	0	0	0	12	170	0	0	540	360	0	15.155°
183	15378.166571028	${\displaystyle C_{1}}$	0.000467899	0	0	12	171	0	0	543	362	0	14.747°
184	15550.421450311	${\displaystyle T}$	0	0	0	12	172	0	0	546	364	0	14.932°
185	15723.720074072	${\displaystyle C_{2}}$	0.000389762	0	0	12	173	0	0	549	366	0	14.775°
186	15897.897437048	${\displaystyle C_{1}}$	0.000389762	0	0	12	174	0	0	552	368	0	14.739°
187	16072.975186320	${\displaystyle D_{5}}$	0	0	0	12	175	0	0	555	370	0	14.848°
188	16249.222678879	${\displaystyle D_{2}}$	0	0	0	12	176	0	0	558	372	0	14.740°
189	16426.371938862	${\displaystyle C_{2}}$	0.000020732	0	0	12	177	0	0	561	374	0	14.671°
190	16604.428338501	${\displaystyle C_{3}}$	0.000586804	0	0	12	178	0	0	564	376	0	14.501°
191	16783.452219362	${\displaystyle C_{1}}$	0.001129202	0	0	13	177	1	0	567	378	0	14.195°
192	16963.338386460	${\displaystyle I}$	0	0	0	12	180	0	0	570	380	0	14.819°	geodesic sphere {3,5+}3,2
193	17144.564740880	${\displaystyle C_{2}}$	0.000985192	0	0	12	181	0	0	573	382	0	14.144°
194	17326.616136471	${\displaystyle C_{1}}$	0.000322358	0	0	12	182	0	0	576	384	0	14.350°
195	17509.489303930	${\displaystyle D_{3}}$	0	0	0	12	183	0	0	579	386	0	14.375°
196	17693.460548082	${\displaystyle C_{2}}$	0.000315907	0	0	12	184	0	0	582	388	0	14.251°
197	17878.340162571	${\displaystyle D_{5}}$	0	0	0	12	185	0	0	585	390	0	14.147°
198	18064.262177195	${\displaystyle C_{2}}$	0.000011149	0	0	12	186	0	0	588	392	0	14.237°
199	18251.082495640	${\displaystyle C_{1}}$	0.000534779	0	0	12	187	0	0	591	394	0	14.153°
200	18438.842717530	${\displaystyle D_{2}}$	0	0	0	12	188	0	0	594	396	0	14.222°
201	18627.591226244	${\displaystyle C_{1}}$	0.001048859	0	0	13	187	1	0	597	398	0	13.830°
202	18817.204718262	${\displaystyle D_{5}}$	0	0	0	12	190	0	0	600	400	0	14.189°
203	19007.981204580	${\displaystyle C_{s}}$	0.000600343	0	0	12	191	0	0	603	402	0	13.977°
204	19199.540775603	${\displaystyle T_{h}}$	0	0	0	12	192	0	0	606	404	0	14.291°
212	20768.053085964	${\displaystyle I}$	0	0	0	12	200	0	0	630	420	0	14.118°	geodesic sphere {3,5+}4,1
214	21169.910410375	${\displaystyle T}$	0	0	0	12	202	0	0	636	424	0	13.771°
216	21575.596377869	${\displaystyle D_{3}}$	0	0	0	12	204	0	0	642	428	0	13.735°
217	21779.856080418	${\displaystyle D_{5}}$	0	0	0	12	205	0	0	645	430	0	13.902°
232	24961.252318934	${\displaystyle T}$	0	0	0	12	220	0	0	690	460	0	13.260°
255	30264.424251281	${\displaystyle D_{3}}$	0	0	0	12	243	0	0	759	506	0	12.565°
256	30506.687515847	${\displaystyle T}$	0	0	0	12	244	0	0	762	508	0	12.572°
257	30749.941417346	${\displaystyle D_{5}}$	0	0	0	12	245	0	0	765	510	0	12.672°
272	34515.193292681	${\displaystyle I_{h}}$	0	0	0	12	260	0	0	810	540	0	12.335°	geodesic sphere {3,5+}3,3
282	37147.294418462	${\displaystyle I}$	0	0	0	12	270	0	0	840	560	0	12.166°	geodesic sphere {3,5+}4,2
292	39877.008012909	${\displaystyle D_{5}}$	0	0	0	12	280	0	0	870	580	0	11.857°
306	43862.569780797	${\displaystyle T_{h}}$	0	0	0	12	294	0	0	912	608	0	11.628°
312	45629.313804002	${\displaystyle C_{2}}$	0.000306163	0	0	12	300	0	0	930	620	0	11.299°
315	46525.825643432	${\displaystyle D_{3}}$	0	0	0	12	303	0	0	939	626	0	11.337°
317	47128.310344520	${\displaystyle D_{5}}$	0	0	0	12	305	0	0	945	630	0	11.423°
318	47431.056020043	${\displaystyle D_{3}}$	0	0	0	12	306	0	0	948	632	0	11.219°
334	52407.728127822	${\displaystyle T}$	0	0	0	12	322	0	0	996	664	0	11.058°
348	56967.472454334	${\displaystyle T_{h}}$	0	0	0	12	336	0	0	1038	692	0	10.721°
357	59999.922939598	${\displaystyle D_{5}}$	0	0	0	12	345	0	0	1065	710	0	10.728°
358	60341.830924588	${\displaystyle T}$	0	0	0	12	346	0	0	1068	712	0	10.647°
372	65230.027122557	${\displaystyle I}$	0	0	0	12	360	0	0	1110	740	0	10.531°	geodesic sphere {3,5+}4,3
382	68839.426839215	${\displaystyle D_{5}}$	0	0	0	12	370	0	0	1140	760	0	10.379°
390	71797.035335953	${\displaystyle T_{h}}$	0	0	0	12	378	0	0	1164	776	0	10.222°
392	72546.258370889	${\displaystyle C_{1}}$	0	0	0	12	380	0	0	1170	780	0	10.278°
400	75582.448512213	${\displaystyle T}$	0	0	0	12	388	0	0	1194	796	0	10.068°
402	76351.192432673	${\displaystyle D_{5}}$	0	0	0	12	390	0	0	1200	800	0	10.099°
432	88353.709681956	${\displaystyle D_{3}}$	0	0	0	24	396	12	0	1290	860	0	9.556°
448	95115.546986209	${\displaystyle T}$	0	0	0	24	412	12	0	1338	892	0	9.322°
460	100351.763108673	${\displaystyle T}$	0	0	0	24	424	12	0	1374	916	0	9.297°
468	103920.871715127	${\displaystyle S_{6}}$	0	0	0	24	432	12	0	1398	932	0	9.120°
470	104822.886324279	${\displaystyle S_{6}}$	0	0	0	24	434	12	0	1404	936	0	9.059°

According to a conjecture, if ${\displaystyle P}$ is the polyhedron formed by the convex hull of the solution configuation to the Thomson Problem for ${\displaystyle m}$ electrons and ${\displaystyle q}$ is the number of quadrilateral faces of ${\displaystyle P}$, then ${\displaystyle P}$ has ${\displaystyle f(m)=\delta _{0,m-2}+3(m-2)-q}$ edges. ^{[16] [ clarification needed ]}

References

1. Thomson, Joseph John (March 1904). "On the Structure of the Atom: an Investigation of the Stability and Periods of Oscillation of a number of Corpuscles arranged at equal intervals around the Circumference of a Circle; with Application of the Results to the Theory of Atomic Structure" (PDF). Philosophical Magazine . Series 6. 7 (39): 237–265. doi:10.1080/14786440409463107. Archived from the original (PDF) on 13 December 2013.
2. Smale, S. (1998). "Mathematical Problems for the Next Century". Mathematical Intelligencer. 20 (2): 7–15. CiteSeerX   10.1.1.35.4101 . doi:10.1007/bf03025291. S2CID   1331144.
3. Föppl, L. (1912). "Stabile Anordnungen von Elektronen im Atom". J. Reine Angew. Math. 141 (141): 251–301. doi:10.1515/crll.1912.141.251. S2CID   120309200..
4. Schwartz, Richard (2010). "The 5 electron case of Thomson's Problem". arXiv: 1001.3702 [math.MG].
5. Yudin, V.A. (1992). "The minimum of potential energy of a system of point charges". Discretnaya Matematika. 4 (2): 115–121 (in Russian).; Yudin, V. A. (1993). "The minimum of potential energy of a system of point charges". Discrete Math. Appl. 3 (1): 75–81. doi:10.1515/dma.1993.3.1.75. S2CID   117117450.
6. Andreev, N.N. (1996). "An extremal property of the icosahedron". East J. Approximation. 2 (4): 459–462. MR 1426716, Zbl   0877.51021
7. Atiyah, Michael; Sutcliffe, Paul (2003). "Polyhedra in physics, chemistry and geometry". arXiv: math-ph/0303071 .
8. Landkof, N. S. Foundations of modern potential theory. Translated from the Russian by A. P. Doohovskoy. Die Grundlehren der mathematischen Wissenschaften, Band 180. Springer-Verlag, New York-Heidelberg, 1972. x+424 pp.
9. Hardin, D. P.; Saff, E. B. Discretizing manifolds via minimum energy points. Notices Amer. Math. Soc. 51 (2004), no. 10, 1186–1194
10. Batagelj, Vladimir; Plestenjak, Bor. "Optimal arrangements of n points on a sphere and in a circle" (PDF). IMFM/TCS. Archived from the original (PDF) on 25 June 2018.
11. LaFave Jr, Tim (February 2014). "Discrete transformations in the Thomson Problem". Journal of Electrostatics. 72 (1): 39–43. arXiv: 1403.2592 . doi:10.1016/j.elstat.2013.11.007. S2CID   119309183.
12. Levin, Y.; Arenzon, J. J. (2003). "Why charges go to the Surface: A generalized Thomson Problem". Europhys. Lett. 63 (3): 415. arXiv: cond-mat/0302524 . Bibcode:2003EL.....63..415L. doi:10.1209/epl/i2003-00546-1. S2CID   18929981.
13. Sir J.J. Thomson, The Romanes Lecture, 1914 (The Atomic Theory)
14. LaFave Jr, Tim (2013). "Correspondences between the classical electrostatic Thomson problem and atomic electronic structure". Journal of Electrostatics. 71 (6): 1029–1035. arXiv: 1403.2591 . doi:10.1016/j.elstat.2013.10.001. S2CID   118480104.
15. Kevin Brown. "Min-Energy Configurations of Electrons On A Sphere". Retrieved 2014-05-01.
16. "Sloane's A008486 (see the comment from Feb 03 2017)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2017-02-08.

Notes

• Whyte, L.L. (1952). "Unique arrangements of points on a sphere". Amer. Math. Monthly. 59 (9): 606–611. doi:10.2307/2306764. JSTOR   2306764.
• Cohn, Harvey (1956). "Stability configurations of electrons on a sphere". Math. Comput. 10 (55): 117–120. doi: 10.1090/S0025-5718-1956-0081133-0 .
• Goldberg, Michael (1969). "Stability configurations of electrons on a sphere". Math. Comp. 23 (108): 785–786. doi: 10.1090/S0025-5718-69-99642-2 .
• Erber, T.; Hockney, G. M. (1991). "equilibrium configurations of N equal charges on a sphere". J. Phys. A: Math. Gen. 24 (23): L1369. Bibcode:1991JPhA...24L1369E. doi:10.1088/0305-4470/24/23/008. S2CID   122561279.
• Morris, J. R.; Deaven, D. M.; Ho, K. M. (1996). "Genetic-algorithm energy minimization for point charges on a sphere". Phys. Rev. B. 53 (4): R1740–R1743. Bibcode:1996PhRvB..53.1740M. CiteSeerX   10.1.1.28.93 . doi:10.1103/PhysRevB.53.R1740. PMID   9983695.
• Erber, T.; Hockney, G. M. (1997). "Complex Systems: Equilibrium Configurations of ${\displaystyle N}$ Equal Charges on a Sphere ${\displaystyle (2\leq N\leq 112)}$". Advances in Chemical Physics. Vol. 98. pp. 495–594. doi:10.1002/9780470141571.ch5. ISBN   9780470141571..
• Altschuler, E. L.; Williams, T. J.; Ratner, E. R.; Tipton, R.; Stong, R.; Dowla, F.; Wooten, F. (1997). "Possible global minimum lattice configurations for Thomson's problem of charges on a sphere". Phys. Rev. Lett. 78 (14): 2681–2685. Bibcode:1997PhRvL..78.2681A. doi:10.1103/PhysRevLett.78.2681.
• Bowick, M.; Cacciuto, A.; Nelson, D. R.; Travesset, A. (2002). "Crystalline order on a sphere and the generalized Thomson Problem". Phys. Rev. Lett. 89 (18): 249902. arXiv: cond-mat/0206144 . Bibcode:2002PhRvL..89r5502B. doi:10.1103/PhysRevLett.89.185502. PMID   12398614. S2CID   20362989.
• Dragnev, P. D.; Legg, D. A.; Townsend, D. W. (2002). "Discrete logarithmic energy on the sphere". Pacific J. Math. 207 (2): 345–358. doi: 10.2140/pjm.2002.207.345 ..
• Katanforoush, A.; Shahshahani, M. (2003). "Distributing points on the sphere. I". Exper. Math. 12 (2): 199–209. doi:10.1080/10586458.2003.10504492. S2CID   7306812.
• Wales, David J.; Ulker, Sidika (2006). "Structure and dynamics of spherical crystals characterized for the Thomson problem". Phys. Rev. B. 74 (21): 212101. Bibcode:2006PhRvB..74u2101W. doi:10.1103/PhysRevB.74.212101. S2CID   119932997. Configurations reprinted in Wales, D. J.; Ulker, S. "The Cambridge cluster database".
• Slosar, A.; Podgornik, R. (2006). "On the connected-charges Thomson problem". Europhys. Lett. 75 (4): 631. arXiv: cond-mat/0606765 . Bibcode:2006EL.....75..631S. doi:10.1209/epl/i2006-10146-1. S2CID   119005054.
• Cohn, Henry; Kumar, Abhinav (2007). "Universally optimal distribution of points on spheres". J. Amer. Math. Soc. 20 (1): 99–148. arXiv: math/0607446 . Bibcode:2007JAMS...20...99C. doi:10.1090/S0894-0347-06-00546-7. S2CID   26614691.
• Wales, D. J.; McKay, H.; Altschuler, E. L. (2009). "Defect motifs for spherical topologies". Phys. Rev. B. 79 (22): 224115. Bibcode:2009PhRvB..79v4115W. doi:10.1103/PhysRevB.79.224115.. Configurations reproduced in Wales, D. J.; Ulker, S. "The Cambridge cluster database".
• Ridgway, W. J. M.; Cheviakov, A. F. (2018). "An iterative procedure for finding locally and globally optimal arrangements of particles on the unit sphere". Comput. Phys. Commun. 233: 84–109. Bibcode:2018CoPhC.233...84R. doi:10.1016/j.cpc.2018.03.029. S2CID   52097788.
• Cecka, Cris; Bowick, Mark J.; Middleton, Alan A. "Thomson Problem @ S.U." Archived from the original on 2018-04-09. Retrieved 2009-11-24.
• This webpage contains many more electron configurations with the lowest known energy: https://www.hars.us.