Addressing an instability in unrestricted density functional theory direct dynamics simulations. Issue 8 (26th October 2018)

• Record Type: Journal Article
• Authors: Malpathak, Shreyas; Ma, Xinyou; Hase, William L.
• Is Part Of: Journal of computational chemistry. Volume 40:Issue 8(2019)
• Page Start: 933
• Page End: 936
• Publication Date: 2018-10-26
• Subjects: Chemistry -- Data processing -- Periodicals; 542.85
• DOI: 10.1002/jcc.25604
• Languages: English
• ISSNs: 0192-8651

Abstract

Abstract : In Density Functional Theory (DFT) direct dynamics simulations with Unrestricted Hartree Fock (UHF) theory, triplet instability often emerges when numerically integrating a classical trajectory. A broken symmetry initial guess for the wave function is often used to obtain the unrestricted DFT potential energy surface (PES), but this is found to be often insufficient for direct dynamics simulations. An algorithm is described for obtaining smooth transitions between the open‐shell and the closed‐shell regions of the unrestricted PES, and thus stable trajectories, for direct dynamics simulations of dioxetane and its OCH2 ‐CH2 O singlet diradical. © 2018 Wiley Periodicals, Inc. Abstract : In DFT direct dynamics simulations with UHF theory, triplet instability often emerges when numerically integrating a classical trajectory. A broken symmetry guess is found to be insufficient for direct dynamics simulations involving a diradical intermediate. An algorithm is described for obtaining smooth transitions between the open‐shell and the closed‐shell regions of the unrestricted PES, and thus stable trajectories, for direct dynamics simulations of dioxetane and its OCH2 ‐CH2 O singlet diradical.