Note on an Approximation Treatment for Many-Electron Systems
Chr. Møller,Milton S. Plesset +1 more
TLDR
In this article, a perturbation theory for treating a system of n electrons in which the Hartree-Fock solution appears as the zero-order approximation was developed, and it was shown by this development that the first order correction for the energy and the charge density of the system is zero.Abstract:
A perturbation theory is developed for treating a system of n electrons in which the Hartree-Fock solution appears as the zero-order approximation. It is shown by this development that the first order correction for the energy and the charge density of the system is zero. The expression for the second-order correction for the energy greatly simplifies because of the special property of the zero-order solution. It is pointed out that the development of the higher approximation involves only calculations based on a definite one-body problem.read more
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Projected unrestricted Mo/ller–Plesset second‐order energies
TL;DR: In this paper, a practical scheme for obtaining unrestricted Mo/ller-Plesset energies at second order (UMP2), with spin contamination removed from the wave function, is described and demonstrated.
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Electric‐field effects on the OH vibrational frequency and infrared absorption intensity for water
TL;DR: In this article, the variations of the anharmonic OH frequency and the infrared absorption intensity with field strength have been calculated for the uncoupled OH stretching vibration of a water molecule in a static, homogeneous electric field using ab initio methods at the MP4 level with a nearly saturated basis set.
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Strong correlation in hydrogen chains and lattices using the variational two-electron reduced density matrix method.
TL;DR: The variational 2-RDM method was shown to capture the metal-to-insulator transition and dissociation behavior accurately for all systems and demonstrates that even for 1.0 A bond distances the presence of strong electron correlation requires a multireference method.
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Ab initio quantum chemistry in the molecular model of atomic collisions
A. Macías,A. Riera +1 more
TL;DR: In this paper, the authors present an introduction to the application of ab initio methods of quantum chemistry to the molecular model of atomic collisions, including the choice and calculation of molecular wavefunctions using the well known Self Consistent Field and Configuration Interaction methods; the calculation of dynamical couplings and a detailed study of diabatic states.
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The prediction of spectroscopic properties from quartic correlated force fields: HCCF, HFCO, SiH+3
TL;DR: In this article, the second-order Mo/ller-Plesset method was used to calculate the quadratic force constants for the full quartic fields. But the effects of using large basis sets were examined.