Home About us Contact
|
Home About us Contact | ||
|
|
||
Configuration Interaction Method (configuration + interaction_method)
Selected AbstractsInfrared spectra of water molecule encapsulated inside fullerene studied by instantaneous vibrational analysis,INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 10 2009Kiyoshi Yagi Abstract Instantaneous vibrational analysis (IVA) is proposed for computing the infrared spectrum of dynamically fluctuating system, and applied to a water molecule encapsulated into fullerene (H2O@C60). A molecular dynamics simulation is first carried out to generate an ensemble of configurations averaging the rotational and translational motion of H2O inside fullerene. At each configuration, instantaneous vibrational frequencies of the water molecule are computed by the vibrational configuration interaction method, which are then employed to construct the line-shape of the spectrum. The vibrational spectrum in the OH stretching region is computed at a temperature of 10 and 100 K based on a direct potential energy surface incorporating the electronic structure theory. It is found that the vibrational frequency of the symmetric stretching mode is blue-shifted compared to that of isolated water, whereas that of the asymmetric stretching mode exhibits no shift in average. The relation between IVA and instantaneous normal mode analysis is presented, and their performances are compared. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009 [source] Spin-adapted states: A basis for quantum dot structure calculationINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 1 2006R. D. Muhandiramge Abstract The exact diagonalization method using a spin-adapted basis is employed to calculate the electronic structure of a multi-electron quantum dot. By isolating spin and orbital angular momentum eigenstates, we have significantly reduced the size of the matrices required in comparison with the standard configuration interaction method. A novel approach to the simplification of the interaction integrals that arise in the calculation is also presented, which allows exact evaluation of the Hamiltonian matrix required in the calculations. This Mathematica package permits accurate calculation of energy levels and wave functions for both ground and excited states of multiple electrons confined in a circular quantum dot. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006 [source] A posteriori corrections to multireference limited configuration interaction based on a Brillouin,Wigner perturbative analysisINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 4 2002I. Hubac Abstract A new a posteriori correction to the method of limited configuration interaction is described that attempts to restore a linear scaling with particle number. The corrections are based on an analysis of the limited configuration interaction method in terms of the Brillouin,Wigner perturbation theory using a Lippmann,Schwinger-like equation. The new correction procedure is general and, in this work, the application to the limited multireference configuration interaction approximation is considered in some detail. An illustrative application to the rigid rotation of the diimine molecule is presented and the results are compared with those obtained by employing Davidson-like corrections and the corresponding full configuration interaction energies. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002 [source] Electron localizability indicators ELI and ELIA: The case of highly correlated wavefunctions for the argon atomJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 8 2008Viktor Bezugly Abstract Electron localizability indicators based on the same-spin electron pair density and the opposite-spin electron pair density are studied for correlated wavefunctions of the argon atom. Different basis sets and reference spaces are used for the multireference configuration interaction method following the complete active space calculations aiming at the understanding of the effect of local electron correlation when approaching the exact wavefunction. The populations of the three atomic shells of Ar atom in real space are calculated for each case. © 2007 Wiley Periodicals, Inc. J Comput Chem 29: 1198,1207, 2008 [source] Exchange interaction tuned by electric field in quantum dotsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 4 2009Artur Kwa, niowski Abstract The effect of external electric field on exchange interaction has been studied by a configuration interaction method for electrons localized in double quantum dots. We model the confinement potential by the twocenter power-exponential function, with different range and "softness", which allows us to investigate various types of quantum dots. We have found that , for quantum dots separated by a sufficiently thick barrier , the exchange energy rapidly increases if the electric field increases, for intermediate electric field reaches a maximum, and decreases to zero at high electric fields. We have discussed the physical reasons of this nonmonotonic dependence. The present results show that the exchange coupling between the electrons in quantum dots can be tuned by applying the external electric field (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | ||||||||||