Theoretical Chemistry Accounts

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<span class="mw-page-title-main">Excited state</span> Quantum states with more energy than the lowest possible amount

In quantum mechanics, an excited state of a system is any quantum state of the system that has a higher energy than the ground state. Excitation refers to an increase in energy level above a chosen starting point, usually the ground state, but sometimes an already excited state. The temperature of a group of particles is indicative of the level of excitation.

<span class="mw-page-title-main">Pi bond</span> Type of chemical bond

In chemistry, pi bonds are covalent chemical bonds, in each of which two lobes of an orbital on one atom overlap with two lobes of an orbital on another atom, and in which this overlap occurs laterally. Each of these atomic orbitals has an electron density of zero at a shared nodal plane that passes through the two bonded nuclei. This plane also is a nodal plane for the molecular orbital of the pi bond. Pi bonds can form in double and triple bonds but do not form in single bonds in most cases.

<span class="mw-page-title-main">MOLPRO</span>

MOLPRO is a software package used for accurate ab initio quantum chemistry calculations. It is developed by Peter Knowles at Cardiff University and Hans-Joachim Werner at Universität Stuttgart in collaboration with other authors.

Oktay Sinanoğlu was a Turkish physical chemist and molecular biophysicist who made significant contributions to the theory of electron correlation in molecules, quantum chemistry, and the theory of solvation.

John Wilfrid Linnett FRS was Vice-Chancellor at the University of Cambridge from 1973 to 1975. He was for many years a Fellow of the Queen's College, Oxford, and a demonstrator in Inorganic Chemistry at the University of Oxford.

Semi-empirical quantum chemistry methods are based on the Hartree–Fock formalism, but make many approximations and obtain some parameters from empirical data. They are very important in computational chemistry for treating large molecules where the full Hartree–Fock method without the approximations is too expensive. The use of empirical parameters appears to allow some inclusion of electron correlation effects into the methods.

<span class="mw-page-title-main">Plumbane</span> Chemical compound

Plumbane, PbH4, is a metal hydride and group 14 hydride composed of lead and hydrogen. Plumbane is not well characterized or well known, and it is thermodynamically unstable with respect to the loss of a hydrogen atom. Derivatives of plumbane include lead tetrafluoride, PbF4, and tetraethyllead, (CH3CH2)4Pb.

<span class="mw-page-title-main">Positronium hydride</span> Exotic molecule consisting of a hydrogen atom bound to a positronium atom

Positronium hydride, or hydrogen positride is an exotic molecule consisting of a hydrogen atom bound to an exotic atom of positronium. Its formula is PsH. It was predicted to exist in 1951 by A Ore, and subsequently studied theoretically, but was not observed until 1990. R. Pareja, R. Gonzalez from Madrid trapped positronium in hydrogen laden magnesia crystals. The trap was prepared by Yok Chen from the Oak Ridge National Laboratory. In this experiment the positrons were thermalized so that they were not traveling at high speed, and they then reacted with H ions in the crystal. In 1992 it was created in an experiment done by David M. Schrader and F.M. Jacobsen and others at the Aarhus University in Denmark. The researchers made the positronium hydride molecules by firing intense bursts of positrons into methane, which has the highest density of hydrogen atoms. Upon slowing down, the positrons were captured by ordinary electrons to form positronium atoms which then reacted with hydrogen atoms from the methane.

<span class="mw-page-title-main">Hermann Hartmann</span>

Hermann Hartmann was a German chemist and professor and researcher in physical and theoretical chemistry at the University of Frankfurt am Main. He contributed to all fields of physical chemistry and was instrumental in establishing theoretical chemistry by developing Ligand field theory (1947) and other quantum chemical models including the Hartmann Potential (1971). He also formulated a new perturbation theory (1970–1977) as part of his pioneering research towards a unified field theory of chemical bonding based on a non-linear Schrödinger equation (1980).

Thomas R. Cundari is regents professor of chemistry at the University of North Texas and co-director of the Center for Advanced Scientific Computing and Modeling (CASCaM).

<span class="mw-page-title-main">Caterpillar tree</span> Tree graph with all nodes within distance 1 from central path

In graph theory, a caterpillar or caterpillar tree is a tree in which all the vertices are within distance 1 of a central path.

<span class="mw-page-title-main">Donald Truhlar</span>

Donald Gene Truhlar is an American scientist working in theoretical and computational chemistry and chemical physics with special emphases on quantum mechanics and chemical dynamics.

<span class="mw-page-title-main">Propalene</span> Chemical compound

Propalene or bicyclo[1.1.0]buta-1,3-diene is a polycyclic hydrocarbon composed of two fused cyclopropene rings. Computational studies indicate that the molecule is planar, with the carbon framework forming a parallelogram that has distinctly alternating short and long carbon–carbon bonds.

Péter R. Surján is a Hungarian theoretical chemist who is known for his research on application of the theory of second quantization in quantum chemistry. In 2016 a festschrift from Theoretical Chemistry Accounts journal was published in his name which is also published as a book in Highlights in Theoretical Chemistry series by the Springer Nature. He is currently a professor and a former dean of the Faculty of Science of the Eötvös Loránd University.

<span class="mw-page-title-main">Christopher J. Cramer</span> American university vice president and research scientist, born 1961

Christopher J. Cramer is a research chemist and served as Vice President for Research at the University of Minnesota from 2018–2021. He presently serves as Senior Vice President and Chief Research Officer for Underwriters Laboratories Inc.

Jiří Čížek is a distinguished emeritus professor at University of Waterloo in Canada. Together with colleague Josef Paldus, in 1966 he reformulated the coupled cluster method for the study of electron correlation in atoms and molecules. He is a Fellow of the Royal Society of Canada and has been honored by the International Academy of Quantum Molecular Science.

A nitrate nitrite, or nitrite nitrate, is a coordination complex or other chemical compound that contains both nitrite and nitrate anions (NO3 and NO2). They are mixed-anion compounds, and they are mixed-valence compounds. Some have third anions. Many nitrite nitrate compounds are coordination complexes of cobalt. Such a substance was discovered by Wolcott Gibbs and Frederick Genth in 1857.

Scandium phosphide is an inorganic compound of scandium and phosphorus with the chemical formula ScP.

References

  1. Journal Citation Reports, 2015
  2. Lim, T. K.; Whitehead, M. A. (1967). "Modus Computandi Eigenvectores et Eigenaestimationes e Matrice Densitatis". Theoretica Chimica Acta. 7 (1): 1–3. doi:10.1007/BF00537361.
  3. Suard, Michèle; Berthier, Gaston; Re, Giuseppe (1967). "Nova methodus adhibendi approximationem molecularium orbitalium ad plures iuxtapositas unitates". Theoretica Chimica Acta. 7 (3): 236–244. doi:10.1007/BF01045581.
  4. Smith, Derek W. (1970). "De structura electronica et stereochimica ionis Cu(NO2)64-". Theoretica Chimica Acta. 17: 89–90. doi:10.1007/BF00526769.