title: Geometry Optimization with Multilayer Methods Using Least-Squares Minimization.
abstract: In this article, we introduce a least-squares minimization scheme for optimizing molecular structures with mixed quantum mechanics (QM) and molecular mechanics (MM) multilayer models. A mixed-coordinate optimization framework was developed. The QM and MM regions are modeled with redundant internal coordinates and Cartesian coordinates, respectively. Within this mixed-coordinate system, a least-squares minimization method using the quasi-Newton step as the evaluation of error is constructed. The couplings between layers are treated rigidly in accordance with the mechanical embedding approach, and the MM Hessian is approximated as a scalar constant of the root-mean-square QM Hessian eigenvalues. Both two-layer and three-layer models were tested. The performance of the method developed herein shows consistently stable and fast convergence.
authors.affiliation: Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States and Gaussian Incorporated, 340 Quinnipiac Street, Building 40, Wallingford, Connecticut 06492, United States.
authors.forename: Wenkel
authors.initials: W
authors.lastname: Liang
authors.affiliation: Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States and Gaussian Incorporated, 340 Quinnipiac Street, Building 40, Wallingford, Connecticut 06492, United States.
authors.forename: Craig T
authors.initials: CT
authors.lastname: Chapman
authors.affiliation: Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States and Gaussian Incorporated, 340 Quinnipiac Street, Building 40, Wallingford, Connecticut 06492, United States.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Frisch
authors.affiliation: Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States and Gaussian Incorporated, 340 Quinnipiac Street, Building 40, Wallingford, Connecticut 06492, United States.
authors.forename: Xiaosong
authors.initials: X
authors.lastname: Li