QMC Meeting

Wednesday Mar 31, 2021, 10:30 AM → 11:30 AM America/New_York

Speaker: Verena A. Neufeld, Columbia University. 

Title: Accelerating the spawn step and convergence in full configuration interaction quantum Monte Carlo

Abstract: In the past decade, full configuration interaction quantum Monte Carlo (FCIQMC)[1] has enabled calculations of systems far beyond the reach of deterministic FCI. In my talk, I will describe improvements of the FCIQMC and closely related coupled cluster Monte Carlo[2]  algorithms. In particular, this includes improving the importance sampling of the off-diagonal (“spawn”) step, by combining the computationally efficient heat bath excitation generator with the memory efficient Cauchy-Schwarz or Power-Pitzer excitation generators [3-5]. I will also describe a development towards accelerating the convergence to a ground state energy estimate by using a quasi-Newton approach inspired by conventional coupled cluster [6].

[1] Booth, G. H.,  et al. JCP 131, 054106 (2009), doi:10.1063/1.3193710.
[2] Thom, A. J. W. PRL 105, 263004 (2010), doi:10.1103/PhysRevLett.105.263004.
[3] Holmes, A. A., et al. JCTC 12, 1561 (2016), doi:10.1021/acs.jctc.5b01170.
[4] Guther, K., et al. JCP 153, 034107 (2020), doi:10.1063/5.0005754.
[5] Neufeld, V. A. and Thom, A. J. W. JCTC 15, 127 (2019), doi:10.1021/acs.jctc.8b00844.
[6] Neufeld, V. A. and Thom, A. J. W. JCTC 16, 1503 (2020), doi:10.1021/acs.jctc.9b01023.