Reviving an old idea of Boys and Handy: the transcorrelated method in the context of FCIQMC – Professor Ali Alavi, University of Cambridge

May 8, 2019 @ 2:15 pm – 3:15 pm
Department of Chemistry
Unilever lecture theatre
Lisa Masters

Over fifty years ago, Boys and Handy (of this department) proposed a non-unitary similarity transformation
of the Schrodinger Hamiltonian, as a means to tackle the
electron correlation problem. The resulting Hamiltonian is non-Hermitian, and their idea
ran into severe technical difficulties due to optimisations problems within a Slater-Jastrow
framework. We re-visit their idea, using FCIQMC to solve the resulting effective Hamiltonian.
We show that this approach obviates the difficulties they encountered,
as well as resulting in increased accuracy due to the FCI
nature of the method. The resulting methodology results in dramatically improved basis
set convergence for ab initio Hamiltonians, as well as being applicable to strongly correlated
electronic systems.