Results 251 to 260 of about 787,470 (297)

Resonances in atoms and molecules

Physics Today, 1979
Observing resonances in cross-section-versus-energy curves has long been a way of life for nuclear and particle physicists, for whom this is often the only way to detect short-lived quantum states. Atomic physicists, on the other hand, have traditionally used other means for observing internal energy states of atoms and molecules. But sixteen years ago
Manfred A. Biondi, Arvid Herzenberg, Chris E. Kuyatt   +2 more
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Similarity of atoms in molecules

Journal of the American Chemical Society, 1993
Similarity of atoms in molecules is quantitatively assessed with a measure that employs electron densities within respective atomic basins. This atomic similarity measure does not rely on arbitrary assumptions concerning basis functions or 'atomic orbitals', is relatively inexpensive to compute, and has straightforward interpretation.
Jerzy Cioslowski, Asiri Nanayakkara
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Properties of atoms in molecules: Atoms under pressure

The Journal of Chemical Physics, 1997
The in situ pressure acting on the surface of an open system at the atomic level is defined and determined by the virial theorem for a proper open system, one whose spatial boundary and equations of motion are determined by the principle of stationary action.
R. F. W. Bader, M. A. Austen
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Atoms in molecules and crystals

Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences, 1951
A new approach to the problems of the electronic structure of molecules is proposed. The basis for this treatment is the observation that the energies of atomization of molecules are small relative to their total energies. Accordingly, a perturbation theory is developed in which the unperturbed states consist of isolated atoms and ions, and the mutual ...
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Properties of atoms in molecules

Theoretica Chimica Acta, 1971
The electronic charges and the positions of the centers of these charges have been calculated for the atoms of a number of second- and third-row heteronuclear diatomic molecules. For both the oxygen and the fluorine atoms, the charge associated with one of these atoms can be correlated, within a series of molecules containing that atom, with both the ...
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Are There Atomic Orbitals in a Molecule?

The Journal of Physical Chemistry A, 2011
Effective atomic orbitals (AOs) have been calculated by the method of the "fuzzy atoms" analysis by using the numerical molecular orbitals (MOs) obtained from plane-wave DFT calculation, i.e., without introducing any atom-centered functions. The results show that in the case of nonhypervalent atoms there are as many effective AOs with non-negligible ...
I, Mayer, I, Bakó, A, Stirling
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Atoms and Molecules in Astrophysics

Physics Bulletin, 1973
T R Carson and M J Roberts London: Academic Press 1973 pp xiv + 367 price £7.50 This volume consists of accounts of some of the lectures and seminars given at the 12th Scottish universities' summer school in physics which was held at the University of Stirling in 1971.
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“Atoms” in molecules and solids

Physics Letters A, 1997
Abstract An “atom” in a composed system is defined by its atomic potential. Using density functional theory in the local density approximation Becke's scheme is applied to decompose the total potential of the system into atomic contributions. Atomic potentials are generally short-ranged.
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Correlations in Atoms and Molecules

1991
Electron correlations have a strong influence on the bonding properties of atoms. Although the correlation energy is usually very small compared to the large SCF energy, it is often of the same order of magnitude as the energy differences one wants to calculate.
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Ab initio computations in atoms and molecules

IBM Journal of Research and Development, 1965
The present status of ab initio computations for atomic and molecular wave functions is analyzed in this paper, with special emphasis on the work done at the IBM Research Laboratory, San Jose. The Roothaan-Hartree-Fock method has been described in detail for atomic systems.
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