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Please use this identifier to cite or link to this item: http://hdl.handle.net/10119/16060

Title: Diffusion Monte Carlo study of para-diiodobenzene polymorphism revisited
Authors: Hongo, Kenta
Watson, Mark A.
Iitaka, Toshiaki
Aspuru-Guzik, Alán
Maezono, Ryo
Keywords: Quantum Chemistry
Diffusion Monte Carlo
Finite Size Errors
Molec-ular Crystals
Polymorphism
Issue Date: 2015-02-05
Publisher: American Chemical Society
Magazine name: Journal of Chemical Theory and Computation
Volume: 11
Number: 3
Start page: 907
End page: 917
DOI: 10.1021/ct500401p
Abstract: We revisit our investigation of the diffusion Monte Carlo (DMC) simulation of p-DIB molecular crystal polymorphism. [J. Phys. Chem. Lett. 2010, 1, 1789-1794] We show that the DFT local density approximation trial nodal surface of the small (1 × 1 × 1) simulation cell used in that work has a considerable dependence on finite-size errors, and, apparently, the final result was fortuitously accurate. We therefore perform a DMC calculation with a 1 × 3 × 3 simulation cell, which is the largest possible using our available supercomputer memory. We use a DFT nodal surface generated with the PBE functional and we accumulate statistical samples with ∼6.4 ×10^5 core hours for each polymorph. Finally, we find from our DMC/ 1 × 3 × 3 calculations that the resulting polymorph stability is consistent with our previous result, as well as experiment. We analyze the finite size errors using model periodic Coulomb interactions and kinetic energy corrections according to the CCMH scheme of Chiesa, Ceperley, Martin, and Holzmann. We investigate the dependence of the finite size errors on different aspect ratios of the simulation cell (k-mesh convergence) in order to understand how to choose the appropriate ratio for the DMC calculations. Although the finite size errors in the DMC total energies are far larger than the energy difference between the two polymorphs, error cancellation means that the polymorph prediction is unchanged. It turns out that the T-move scheme is essential for our large-sized DMC simulations in order to circumvent population explosions and large time-step bias.
Rights: Kenta Hongo , Mark A. Watson , Toshiaki Iitaka , Alán Aspuru-Guzik ,and Ryo Maezono, Journal of Chemical Theory and Computation, 2015, 11(3), pp.907-917. This document is the unedited author's version of a Submitted Work that was subsequently accepted for publication in Journal of Chemical Theory and Computation, copyright (c) American Chemical Society after peer review. To access the final edited and published work, see http://dx.doi.org/10.1021/ct500401p
URI: http://hdl.handle.net/10119/16060
Material Type: author
Appears in Collections:b10-1. 雑誌掲載論文 (Journal Articles)

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