Electron correlation from path resummations: the double-excitation star.
Resummation over a selected subset of paths allows the approximate evaluation of an N-electron path-integral. In particular, we show that the double excitation star graph, consisting of all doubly excited determinants attached to the reference Hartree-Fock determinant, has an energy which is easily calculated in O[N4] time after integral precomputation, and produces binding curves of a similar quality to CCSD theory for a range of systems including the N2 molecule, the hydrogen-bonded water dimer, and dispersion dominated Ne2 and Ar2 dimers.
University of Cambridge, Chemistry Department, Lensfield Road, Cambridge, UK CB2 1EW. ajwt3@cam.ac.uk
Alex J W
AJ
Thom
George H
GH
Booth
Ali
A
Alavi