Fast electron correlation methods for molecular clusters without basis set superposition errors

2008 ◽  
Vol 128 (7) ◽  
pp. 074103 ◽  
Author(s):  
Muneaki Kamiya ◽  
So Hirata ◽  
Marat Valiev
Keyword(s):  
Electron Correlation ◽  
Fast Electron ◽  
Molecular Clusters ◽  
Basis Set ◽  
Correlation Methods

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

scholarly journals THE INTERACTION OF Co2+-AMMONIA MODELLING: THE COMPARATIVE STUDY BETWEEN AB INITIO AND ELECTRON CORRELATION METHODS

2010 ◽  
Vol 2 (2) ◽  
pp. 67-73
Author(s):  
Harno Dwi Pranowo ◽  
Foliatini Foliatini ◽  
Karna Wijaya
Keyword(s):  
Charge Transfer ◽  
Comparative Study ◽  
Electron Correlation ◽  
Transfer Effect ◽  
Basis Set ◽  
Basis Sets ◽  
Complex Energy ◽  
Hartree Fock ◽  
Correlation Methods ◽  
The Comparative Study

Research on comparison between Hartree-Fock method and electron correlation methods as well as the effect of size of basis sets on representing interaction of Co2+-NH3 observed from complex energy parameters and optimum geometric parameters have been carried out.The first step is screening basis sets based on charge transfer effect and BSSE value. The selected basis set does not yield charge transfer at 1,4 Å  

Nonnuclear Maxima in the Charge Density

1993 ◽  
Vol 48 (1-2) ◽  
pp. 127-133 ◽  
Author(s):  
Kenneth E. Edgecombe ◽  
Vedene H. Smith, Jr. ◽  
Florian Müller-Plathe
Keyword(s):  
Charge Density ◽  
Electron Density ◽  
Electron Correlation ◽  
Basis Set ◽  
Valence Shell ◽  
Correlation Effects ◽  
Electron Correlation Effects

Abstract Basis-set and electron-correlation effects on the appearance and disappearance of nonnuclear maxima in the electron density are examined in Li2 , Na2 , Na4 and Na5 . It is shown that nonnuclear attractors can be removed in all cases except Li2 . The appearance of a pseudoatom in a lithium molecule correlates remarkably well with the size of the region, in an atomic calculation, of V2r(r) for the valence shell of the atom. This and the fact that the pseudoatom is also present in the promolecule indicate that the pseudoatoms are remnants of, or in fact are portions of, atoms that are not perturbed enough in the molecule to remove an essentially atomic characteristic.

scholarly journals Origin Invariant Full Optical Rotation Tensor in the Length Dipole Gauge without London Atomic Orbitals

2021 ◽  
Author(s):  
Marco Caricato
Keyword(s):  
Electron Correlation ◽  
Density Functional ◽  
Optical Rotation ◽  
Density Functional Method ◽  
Functional Method ◽  
Basis Set ◽  
Rotation Tensor ◽  
Atomic Orbitals ◽  
Complete Basis Set ◽  
Approximate Wave

<div> <div> <div> <p>We present an origin-invariant approach to compute the full optical rotation tensor (Buckingham/Dunn tensor) in the length dipole gauge without recourse to London atomic orbitals, called LG(OI). The LG(OI) approach is simpler and less computationally demanding than the more common LG-London and modified velocity gauge (MVG) approaches and it can be used with any approximate wave function or density functional method. We report an implementation at coupled cluster with single and double excitations level (CCSD), for which we present the first simulations of the origin-invariant Buckingham/Dunn tensor in the length gauge. With this method, we attempt to decouple the effects of electron correlation and basis set incompleteness on the choice of gauge for optical rotation calculations on simple test systems. The simulations show a smooth convergence of the LG(OI) and MVG results with the basis set size towards the complete basis set limit. However, these preliminary results indicate that CCSD may not be close to a complete description of the electron correlation effects on this property even for small molecules, and that basis set incompleteness may be a less important cause of discrepancy between choices of gauge than electron correlation incompleteness. </p> </div> </div> </div>

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