Fully relativistic complete active space self-consistent field for large molecules: Quasi-second-order minimax optimization

Jefferson E. Bates, Toru Shiozaki

Research output: Contribution to journalArticle

20 Scopus citations

Abstract

We develop an efficient algorithm for four-component complete active space self-consistent field (CASSCF) methods on the basis of the Dirac equation that takes into account spin-orbit and other relativistic effects self-consistently. Orbitals are optimized using a trust-region quasi-Newton 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 heavy-elements. 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 state-averaged variant.

Original languageEnglish (US)
Article number044112
JournalJournal of Chemical Physics
Volume142
Issue number4
DOIs
StatePublished - Jan 28 2015

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

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