Angular aspects of electron correlation and the Coulomb hole. II. The 2 1S and the 2 3S excited states of helium

1987 ◽  
Vol 87 (2) ◽  
pp. 1216-1219 ◽  
Author(s):  
J. M. Ugalde ◽  
Russell J. Boyd ◽  
John S. Perkyns
Keyword(s):  
Excited States ◽  
Electron Correlation ◽  
Coulomb Hole

Excitation Energies from a Partially Spin-Restricted Wave Function

2007 ◽  
Vol 3 (1) ◽  
pp. 65-69 ◽  
Author(s):  
V.N. Glushkov
Keyword(s):  
Wave Function ◽  
Excited States ◽  
Electron Correlation ◽  
Electronic Excitation ◽  
Slater Determinant ◽  
Molecular Orbitals ◽  
Reference Configuration ◽  
Excitation Energies ◽  
Hartree Fock ◽  
Natural Base

A singe Slater determinant consisting of restricted and unrestricted, in spins, parts is proposed to construct a reference configuration for singlet excited states having the same symmetry as the ground one. A partially restricted Hartree-Fock approach is developed to derive amended equations determining the spatial molecular orbitals for singlet excited states. They present the natural base to describe the electron correlation in excited states using the wellestablished spin-annihilated perturbation theories. The efficiency of the proposed method is demonstrated by calculations of electronic excitation energies for the Be atom and LiH molecule.

The structures and stabilities of singlet and triplet dithiatriazines: a computational study

1988 ◽  
Vol 66 (9) ◽  
pp. 2279-2284 ◽  
Author(s):  
R. E. Hoffmeyer ◽  
W.-T. Chan ◽  
J. D. Goddard ◽  
R. T. Oakley
Keyword(s):  
Excited States ◽  
Electron Correlation ◽  
Computational Study ◽  
Geometry Optimization ◽  
Hartree Fock ◽  
Structural Distortions ◽  
Energy Gaps ◽  
Jahn Teller ◽  
Moller Plesset ◽  
Triplet Excited States

Ab initio molecular orbital and Møller–Plesset perturbation theory calculations have been carried out on two model dithiatriazines RCN3S2 (R = H, NH2). With geometry optimization and the inclusion of electron correlation both of these dithiatriazines are predicted to be ground state singlets. Both molecules have low-lying triplet excited states, with energy gaps of 6.6 (R = H) and 13.0 (R = NH2) kcal mol−1. The singlet dithiatriazines distort from high (C2v) to low (Cs) symmetry, and these changes are important in determining the relative energies of the singlet and triplet molecules. The structural distortions experienced by these molecules are related to Hartree–Fock and Jahn–Teller instabilities in other thiazene heterocycles.

scholarly journals Ultrafast and radiationless electronic excited state decay of uracil and thymine cations: computing the effects of dynamic electron correlation

2019 ◽  
Vol 21 (26) ◽  
pp. 14322-14330 ◽  
Author(s):  
Javier Segarra-Martí ◽  
Thierry Tran ◽  
Michael J. Bearpark
Keyword(s):  
Excited State ◽  
Excited States ◽  
Electron Correlation ◽  
Electronic Excited States ◽  
Electronic Excited State ◽  
State Decay ◽  
Radiationless Decay

In this article we characterise the radiationless decay of the first few electronic excited states of the cations of DNA/RNA nucleobases uracil and thymine, including the effects of dynamic electron correlation on energies and geometries (optimised with XMS-CASPT2).

Fast electron correlation methods for molecular clusters in the ground and excited states

2005 ◽  
Vol 103 (15-16) ◽  
pp. 2255-2265 ◽  
Author(s):  
So Hirata † ◽  
Marat Valiev ◽  
Michel Dupuis ◽  
Sotiris S. Xantheas ◽  
Shinichiro Sugiki ◽  
...  
Keyword(s):  
Excited States ◽  
Electron Correlation ◽  
Fast Electron ◽  
Molecular Clusters ◽  
Correlation Methods

Electron correlation and molecular dynamics for excited states and photochemistry

2008 ◽  
Vol 349 (1-3) ◽  
pp. vii-viii ◽  
Author(s):  
Mario Barbatti ◽  
Horst Köppel ◽  
Ron Shepard ◽  
Péter G. Szalay
Keyword(s):  
Molecular Dynamics ◽  
Excited States ◽  
Electron Correlation

scholarly journals Fine Structure of the 1s2s2p 4P0 and 1s2p2 4P Doubly Excited States of Lithiumlike Si XII

1988 ◽  
Vol 102 ◽  
pp. 111-114
Author(s):  
J.P. Buchet ◽  
M.C. Buchet-Poulizac ◽  
A. Denis ◽  
J. Désesquelles ◽  
M. Druetta ◽  
...  
Keyword(s):  
Fine Structure ◽  
Excited States ◽  
Electron Correlation ◽  
Ion Beam ◽  
Correlation Effects ◽  
Doubly Excited States ◽  
Doubly Excited ◽  
Electron Correlation Effects ◽  
Far Ultraviolet ◽  
Fast Ion

AbstractThe ls2s2p4P0- ls2p24P transitions of Si XII have been investigated using fast ion beam spectroscopy in the far ultraviolet. The results for fine structure intervals and term separation represent the highest Z test of electron correlation effects and relativistic contributions in doubly excited states of lithiumlike ions.

Coulomb hole in some excited states of helium

1973 ◽  
Vol 6 (5) ◽  
pp. 782-793 ◽  
Author(s):  
R J Boyd ◽  
C A Coulson
Keyword(s):  
Excited States ◽  
Coulomb Hole
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