Krishnan Raghavachari

Assessment of Gaussian-2 and density functional theories for the computation of ionization potentials and electron affinities

A set of 146 well-established ionization potentials and electron affinities is presented. This set, referred to as the G2 ion test set, includes the 63 atoms and molecules whose...

Gaussian-3X (G3X) theory: Use of improved geometries, zero-point energies, and Hartree–Fock basis sets

A modification of G3 theory incorporating three changes is presented. The three new features include: (1) B3LYP/6-31G(2df,p) geometry; (2) B3LYP/6-31G(2df,p) zero-point energy; ...

A fifth-order perturbation comparison of electron correlation theories

Quadratic configuration interaction. A general technique for determining electron correlation energies

A general procedure is introduced for calculation of the electron correlation energy, starting from a single Hartree–Fock determinant. The normal equations of (linear) configura...

An augmented coupled cluster method and its application to the first-row homonuclear diatomics

An augmented coupled cluster scheme to evaluate the higher order electron correlation effects is proposed. The method is carried out in two steps. First, a coupled cluster calcu...