High-level multireference methods in the quantum-chemistry program system COLUMBUS: Analytic MR-CISD and MR-AQCC gradients and MR-AQCC-LRT for excited states, GUGA spin-orbit CI and parallel CI density

H. Lischka, R. Shepard, R. M. Pitzer, I. Shavitt, M. Dallos, T. Müller, P. G. Szalay, M. Seth, G. S. Kedziora, S. Yabushita, Z. Zhang

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Development of several new computational approaches within the framework of multi-reference ab initio molecular electronic structure methodology and their implementation in the COLUMBUS program system are reported. These new features are: calculation of the analytical MR-CI gradient for excited states based on state-averaged MCSCF orbitals, the extension of the MR-ACPF/AQCC methods to excited states in the framework of linear-response theory, spin-orbit CI for molecules containing heavy atoms and the development of a massively-parallel code for the computation of the one- and two-particle density matrix elements. Illustrative examples are given for each of these cases.

Original languageEnglish
Pages (from-to)664-673
Number of pages10
JournalPhysical Chemistry Chemical Physics
Issue number5
Publication statusPublished - 2001 Mar 15


ASJC Scopus subject areas

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

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