Introduction

HANDE [Spencer19] contains optimised, highly parallel implementations of the full configuration interaction quantum Monte Carlo (FCIQMC) [Booth09], coupled cluster Monte Carlo (CCMC) [Thom10] and Density Matrix Quantum Monte Carlo (DMQMC) [Blunt14], [Malone15] algorithms for a variety of systems. Development work continues to add new features and investigate the algorithms and new applications.

HANDE can perform calculations on generic systems such as molecules via an externally generated integral file. The integral file is in the FCIDUMP format [Knowles89], which can be generated by several quantum chemistry codes such as MOLPRO, Q-Chem (with patches from Alex Thom) and PSI4. HANDE can also perform calculations on model Hamiltonians, for which no additional integrals are required. The model Hamiltonians currently available are the Hubbard model, Heisenberg model and uniform electron gas.

Configuration interaction (CI) is also implemented using an external library (lapack/scalapack) and can be performed in both serial and parallel. Note that this is rather slow and intended for debugging purposes only. Most quantum chemistry codes (e.g. PSI4) contain a substantially more powerful and optimised CI implementation.