Fully relativistic complete active space selfconsistent field for large molecules: Quasisecondorder minimax optimization
Abstract
We develop an efficient algorithm for fourcomponent complete active space selfconsistent field (CASSCF) methods on the basis of the Dirac equation that takes into account spin–orbit and other relativistic effects selfconsistently. Orbitals are optimized using a trustregion quasiNewton method with Hessian updates so that energies are minimized with respect to rotations among electronic orbitals and maximized with respect to rotations between electronic and positronic orbitals. Utilizing density fitting and parallel computation, we demonstrate that Dirac–Coulomb CASSCF calculations can be routinely performed on systems with 100 atoms and a few heavyelements. The convergence behavior and wall times for octachloridodirhenate(III) and a tungsten methylidene complex are presented. In addition, the excitation energies of octachloridodirhenate(III) are reported using a stateaveraged variant.
 Authors:
 Department of Chemistry, Northwestern University, 2145 Sheridan Rd., Evanston, Illinois 60208 (United States)
 Publication Date:
 OSTI Identifier:
 22416038
 Resource Type:
 Journal Article
 Resource Relation:
 Journal Name: Journal of Chemical Physics; Journal Volume: 142; Journal Issue: 4; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
 Country of Publication:
 United States
 Language:
 English
 Subject:
 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ALGORITHMS; ATOMS; CONVERGENCE; DIRAC EQUATION; EXCITATION; LS COUPLING; MOLECULES; NEWTON METHOD; OPTIMIZATION; ORGANIC CHLORINE COMPOUNDS; RELATIVISTIC RANGE; RHENATES; ROTATION; SELFCONSISTENT FIELD; SPACE; TUNGSTEN
Citation Formats
Bates, Jefferson E., and Shiozaki, Toru. Fully relativistic complete active space selfconsistent field for large molecules: Quasisecondorder minimax optimization. United States: N. p., 2015.
Web. doi:10.1063/1.4906344.
Bates, Jefferson E., & Shiozaki, Toru. Fully relativistic complete active space selfconsistent field for large molecules: Quasisecondorder minimax optimization. United States. doi:10.1063/1.4906344.
Bates, Jefferson E., and Shiozaki, Toru. 2015.
"Fully relativistic complete active space selfconsistent field for large molecules: Quasisecondorder minimax optimization". United States.
doi:10.1063/1.4906344.
@article{osti_22416038,
title = {Fully relativistic complete active space selfconsistent field for large molecules: Quasisecondorder minimax optimization},
author = {Bates, Jefferson E. and Shiozaki, Toru},
abstractNote = {We develop an efficient algorithm for fourcomponent complete active space selfconsistent field (CASSCF) methods on the basis of the Dirac equation that takes into account spin–orbit and other relativistic effects selfconsistently. Orbitals are optimized using a trustregion quasiNewton method with Hessian updates so that energies are minimized with respect to rotations among electronic orbitals and maximized with respect to rotations between electronic and positronic orbitals. Utilizing density fitting and parallel computation, we demonstrate that Dirac–Coulomb CASSCF calculations can be routinely performed on systems with 100 atoms and a few heavyelements. The convergence behavior and wall times for octachloridodirhenate(III) and a tungsten methylidene complex are presented. In addition, the excitation energies of octachloridodirhenate(III) are reported using a stateaveraged variant.},
doi = {10.1063/1.4906344},
journal = {Journal of Chemical Physics},
number = 4,
volume = 142,
place = {United States},
year = 2015,
month = 1
}

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