title: Evaluating the Accuracy of Hessian Approximations for Direct Dynamics Simulations.
abstract: Direct dynamics simulations are a very useful and general approach for studying the atomistic properties of complex chemical systems, since an electronic structure theory representation of a system's potential energy surface is possible without the need for fitting an analytic potential energy function. In this paper, recently introduced compact finite difference (CFD) schemes for approximating the Hessian [J. Chem. Phys.2010, 133, 074101] are tested by employing the monodromy matrix equations of motion. Several systems, including carbon dioxide and benzene, are simulated, using both analytic potential energy surfaces and on-the-fly direct dynamics. The results show, depending on the molecular system, that electronic structure theory Hessian direct dynamics can be accelerated up to 2 orders of magnitude. The CFD approximation is found to be robust enough to deal with chaotic motion, concomitant with floppy and stiff mode dynamics, Fermi resonances, and other kinds of molecular couplings. Finally, the CFD approximations allow parametrical tuning of different CFD parameters to attain the best possible accuracy for different molecular systems. Thus, a direct dynamics simulation requiring the Hessian at every integration step may be replaced with an approximate Hessian updating by tuning the appropriate accuracy.
authors.affiliation: Department of Computer Science, Texas Tech University, Lubbock, Texas 79409-3104, United States.
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhuang
authors.affiliation: Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409, United States.
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Siebert
authors.affiliation: Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409, United States.
authors.forename: William L
authors.initials: WL
authors.lastname: Hase
authors.affiliation: Department of Chemistry, Bar-Ilan University, Ramat-Gan 52900, Israel.
authors.forename: Kenneth G
authors.initials: KG
authors.lastname: Kay
authors.affiliation: Dipartimento di Chimica, Università degli Studi di Milano, via Golgi 19, 20133 Milano, Italy.
authors.forename: Michele
authors.initials: M
authors.lastname: Ceotto