How to Select Active Space for Multiconfigurational Quantum Chemistry

Bjorn Roos is one of the pioneers in the development and usage of multiconfigurational methods, in particular, the complete active space self-consistent field method and the perturbational complete active space perturbation theory through second order. To perform multiconfigurational calculations using these methods, a set of active orbitals must be selected, and the success of the methods depends on the choice of this set. This is not only sometimes easy but also sometimes difficult, especially for use of the more recent RASSCF and RASPT2 methods (which use a "restricted active space" rather than the complete one). Although an automated procedure for selecting the active orbitals would be a preferable solution, this does not seem feasible yet. An account of the problem is given, with examples and some approaches that usually work. (C) 2011 Wiley Periodicals, Inc. Int J Quantum Chem 111: 3329-3338, 2011 (Less)

[1]  Valera Veryazov,et al.  Not innocent: verdict from ab initio multiconfigurational second-order perturbation theory on the electronic structure of chloroiron corrole. , 2008, The journal of physical chemistry. B.

[2]  I. Gould,et al.  Bonded exciplexes. A new concept in photochemical reactions. , 2007, The Journal of organic chemistry.

[3]  B. Roos,et al.  How accurate is the CASPT2 method? , 2006, Physical chemistry chemical physics : PCCP.

[4]  Hans-Joachim Werner,et al.  Multireference perturbation theory for large restricted and selected active space reference wave functions , 2000 .

[5]  K. Pierloot,et al.  The CASPT2 method in inorganic electronic spectroscopy: from ionic transition metal to covalent actinide complexes* , 2003 .

[6]  B. Roos,et al.  A complete active space SCF method (CASSCF) using a density matrix formulated super-CI approach , 1980 .

[7]  P. Malmqvist,et al.  An ab initio study of aqueous Fe2+–Fe3+ electron transfer , 1992 .

[8]  Francesco Aquilante,et al.  Cholesky Decomposition-Based Multiconfiguration Second-Order Perturbation Theory (CD-CASPT2): Application to the Spin-State Energetics of Co(III)(diiminato)(NPh). , 2008, Journal of chemical theory and computation.

[9]  K. Andersson,et al.  Electric properties of the ozone molecule , 1992 .

[10]  Jeppe Olsen,et al.  Determinant based configuration interaction algorithms for complete and restricted configuration interaction spaces , 1988 .

[11]  R. Cimiraglia,et al.  New perspectives in multireference perturbation theory: the n-electron valence state approach , 2007 .

[12]  Kerstin Andersson,et al.  Second-order perturbation theory with a CASSCF reference function , 1990 .

[13]  Alistair P. Rendell,et al.  The restricted active space self-consistent-field method, implemented with a split graph unitary group approach , 1990 .

[14]  Klaus Ruedenberg,et al.  Localized Atomic and Molecular Orbitals , 1963 .

[15]  M. Head‐Gordon,et al.  Highly correlated calculations with a polynomial cost algorithm: A study of the density matrix renormalization group , 2002 .

[16]  S. F. Boys.  Construction of Some Molecular Orbitals to Be Approximately Invariant for Changes from One Molecule to Another , 1960 .

[17]  Paul G. Mezey,et al.  A fast intrinsic localization procedure applicable for ab initio and semiempirical linear combination of atomic orbital wave functions , 1989 .

[18]  R. Lindh,et al.  The fraternal twins of quartet O+4 , 1994 .

[19]  FRANCESCO AQUILANTE,et al.  MOLCAS 7: The Next Generation , 2010, J. Comput. Chem..

[20]  B. Roos,et al.  A theoretical study of the dissociation energy of Ni2+ A case of broken symmetry , 1996 .