Parallel coupled perturbed CASSCF equations and analytic CASSCF second derivatives

Timothy J. Dudley, Ryan M. Olson, Michael W. Schmidt, Mark S. Gordon

Research output: Contribution to journalArticlepeer-review

22 Scopus citations


A parallel algorithm for solving the coupled-perturbed MCSCF (CPMCSCF) equations and analytic nuclear second derivatives of CASSCF wave functions is presented. A parallel scheme for evaluating derivative integrals and their subsequent use in constructing other derivative quantities is described. The task of solving the CPMCSCF equations is approached using a parallelization scheme that partitions the electronic hessian matrix over all processors as opposed to simple partitioning of the 3 N solution vectors among the processors. The scalability of the current algorithm, up to 128 processors, is demonstrated. Using three test cases, results indicate that the parallelization of derivative integral evaluation through a simple scheme is highly effective regardless of the size of the basis set employed in the CASSCF energy calculation. Parallelization of the construction of the MCSCF electronic hessian during solution of the CPMCSCF equations varies quantitatively depending on the nature of the hessian itself, but is highly scalable in all cases.

Original languageEnglish (US)
Pages (from-to)352-362
Number of pages11
JournalJournal of Computational Chemistry
Issue number3
StatePublished - Feb 2006
Externally publishedYes


  • Analytic harmonic frequencies
  • Parallel algorithm


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