3 years ago

Diagrammatic Coupled Cluster Monte Carlo.

Charles J. C. Scott, Roberto Di Remigio, T. Daniel Crawford, Alex J. W. Thom

We propose a modified coupled cluster Monte Carlo algorithm that stochastically samples connected terms within the truncated Baker-Campbell-Hausdorff expansion of the similarity transformed Hamiltonian by construction of coupled cluster diagrams on the fly. Our new approach - diagCCMC - allows propagation to be performed using only the connected components of the similarity-transformed Hamiltonian, greatly reducing the memory cost associated with the stochastic solution of the coupled cluster equations. We show that for perfectly local, noninteracting systems, diagCCMC is able to represent the coupled cluster wavefunction with a memory cost that scales linearly with system size. The favorable memory cost is observed with the only assumption of fixed stochastic granularity and is valid for arbitrary levels of coupled cluster theory. Significant reduction in memory cost is also shown to smoothly appear with dissociation of a finite chain of helium atoms. Our novel methodology moves the theoretical basis of coupled cluster Monte Carlo closer to deterministic approaches.

Publisher URL: http://arxiv.org/abs/1901.02753

DOI: arXiv:1901.02753v1

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