George D. Purvis

A full coupled-cluster singles and doubles model: The inclusion of disconnected triples

The coupled-cluster singles and doubles model (CCSD) is derived algebraically, presenting the full set of equations for a general reference function explicitly in spin–orbital f...

Many‐body perturbation theory, coupled‐pair many‐electron theory, and the importance of quadruple excitations for the correlation problem

Abstract Many‐body (diagrammatic) perturbation theory ( MBPT ), coupled‐pair many‐electron theory ( CPMET ), and configuration interaction ( CI ) are investigated with particula...

Comparison of MBPT and coupled-cluster methods with full CI. Importance of triplet excitation and infinite summations

The potential energy curve for the <i>X</i>1Σ<i>g</i>+ state of Mg2 calculated with many-body perturbation theory

The ground state potential curve for the van der waals molecule, Mg2, is calculated by adding to the Hartree–Fock potential curve those many-body perturbation theory (MBPT) corr...