TY - JOUR

T1 - Forces from Stochastic Density Functional Theory under Nonorthogonal Atom-Centered Basis Sets

AU - Shpiro, Ben

AU - Fabian, Marcel David

AU - Rabani, Eran

AU - Baer, Roi

AU - Rabani, Eran

AU - Baer, Roi

N1 - Publisher Copyright:
© 2022 American Chemical Society. All rights reserved.

PY - 2022/3/8

Y1 - 2022/3/8

N2 - We develop a formalism for calculating forces on the nuclei within the linear-scaling stochastic density functional theory (sDFT) in a nonorthogonal atom-centered basis set representation (Fabian et al. Wiley Interdiscip. Rev.: Comput. Mol. Sci. 2019, 9, e1412, 10.1002/wcms.1412) and apply it to the Tryptophan Zipper 2 (Trp-zip2) peptide solvated in water. We use an embedded-fragment approach to reduce the statistical errors (fluctuation and systematic bias), where the entire peptide is the main fragment and the remaining 425 water molecules are grouped into small fragments. We analyze the magnitude of the statistical errors in the forces and find that the systematic bias is of the order of 0.065 eV/Å (∼1.2 × 10-3Eh/a0) when 120 stochastic orbitals are used, independently of system size. This magnitude of bias is sufficiently small to ensure that the bond lengths estimated by stochastic DFT (within a Langevin molecular dynamics simulation) will deviate by less than 1% from those predicted by a deterministic calculation.

AB - We develop a formalism for calculating forces on the nuclei within the linear-scaling stochastic density functional theory (sDFT) in a nonorthogonal atom-centered basis set representation (Fabian et al. Wiley Interdiscip. Rev.: Comput. Mol. Sci. 2019, 9, e1412, 10.1002/wcms.1412) and apply it to the Tryptophan Zipper 2 (Trp-zip2) peptide solvated in water. We use an embedded-fragment approach to reduce the statistical errors (fluctuation and systematic bias), where the entire peptide is the main fragment and the remaining 425 water molecules are grouped into small fragments. We analyze the magnitude of the statistical errors in the forces and find that the systematic bias is of the order of 0.065 eV/Å (∼1.2 × 10-3Eh/a0) when 120 stochastic orbitals are used, independently of system size. This magnitude of bias is sufficiently small to ensure that the bond lengths estimated by stochastic DFT (within a Langevin molecular dynamics simulation) will deviate by less than 1% from those predicted by a deterministic calculation.

UR - http://www.scopus.com/inward/record.url?scp=85115703938&partnerID=8YFLogxK

U2 - 10.1021/acs.jctc.1c00794

DO - 10.1021/acs.jctc.1c00794

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C2 - 35099187

AN - SCOPUS:85115703938

SN - 1549-9618

VL - 18

SP - 1458

EP - 1466

JO - Journal of Chemical Theory and Computation

JF - Journal of Chemical Theory and Computation

IS - 3

ER -