Development of a Computational Strategy in Electronic Structure Calculations: Error Analysis in Configuration Interaction Treatments

From a practical point of view one of the most serious problems in the field of atomic and molecular calculations is the need for estimating their reliability in a given application. In all but the simplest of cases an exact treatment is not possible, or at least is not economically feasible, and as a result it is imperative that certain approximations be introduced. The difficulties attendant upon such procedures thus lie not only in providing that the necessary computations be carried out in a technically optimum manner, but also in recognizing to what extent the resulting calculated findings deviate from experimental reality. For people who do not work in the computational field directly and whose main interest lies in the interpretation of experimental data, the second of these problems is by far the more critcal, particularly in view of the great variety of such theoretical treatments which have been brought forward in recent times.

[1]  B. Roos,et al.  A new method for large-scale Cl calculations , 1972 .

[2]  Robert J. Buenker,et al.  Individualized configuration selection in CI calculations with subsequent energy extrapolation , 1974 .

[3]  I. Shavitt,et al.  Selection of terms for a CI wavefunction to preserve potential surface features , 1977 .

[4]  Ernest R. Davidson,et al.  CONFIGURATION INTERACTION DESCRIPTION OF ELECTRON CORRELATION , 1974 .

[5]  Y. Öhrn,et al.  Configuration Interaction Studies of NO and NO+ with Comparisons to Photoelectron Spectra , 1972 .

[6]  B. Roos,et al.  A direct CI method with a multiconfigurational reference state , 1980 .

[7]  H. Lischka,et al.  PNO–CI (pair natural orbital configuration interaction) and CEPA–PNO (coupled electron pair approximation with pair natural orbitals) calculations of molecular systems. I. Outline of the method for closed‐shell states , 1975 .

[8]  Robert J. Buenker,et al.  The ground state of the CN+ ion: a multi-reference Ci study , 1980 .

[9]  F. Grein,et al.  Low‐lying valence states of the PO molecule according to configuration‐interaction calculations , 1973 .

[10]  B. Brooks,et al.  The graphical unitary group approach to the electron correlation problem. Methods and preliminary applications , 1979 .

[11]  Bernard Pullman,et al.  The World of Quantum Chemistry , 1974 .

[12]  Wilfried Meyer,et al.  PNO–CI Studies of electron correlation effects. I. Configuration expansion by means of nonorthogonal orbitals, and application to the ground state and ionized states of methane , 1973 .

[13]  C. Nicolaides,et al.  Excited States in Quantum Chemistry , 1978 .

[14]  Robert J. Buenker,et al.  Energy extrapolation in CI calculations , 1975 .

[15]  S. Peyerimhoff,et al.  Theoretical study of the vertical electronic spectrum of O2: Mixing of valence and Rydberg states , 1975 .

[16]  S. Peyerimhoff,et al.  Ab initio CI study of the stability and electronic spectrum of the HOCl molecule , 1977 .

[17]  Rodney J. Bartlett,et al.  Many‐body perturbation theory, coupled‐pair many‐electron theory, and the importance of quadruple excitations for the correlation problem , 1978 .

[18]  C. Bender.  NATURAL ORBITAL BASED ENERGY CALCULATION FOR HELIUM HYDRIDE AND LITHIUM HYDRIDE , 1966 .

[19]  L. Cederbaum.  Direct calculation of ionization potentials of closed-shell atoms and molecules , 1973 .

[20]  B. Brooks,et al.  The BERKELEY system. III. General configuration‐interaction methods for open‐shell molecular electronic states , 1978 .

[21]  A. Bunge,et al.  Electronic Wavefunctions for Atoms. III. Partition of Degenerate Spaces and Ground State of C , 1970 .

[22]  Harrison Shull,et al.  NATURAL ORBITALS IN THE QUANTUM THEORY OF TWO-ELECTRON SYSTEMS , 1956 .

[23]  Bernard R. Brooks,et al.  The Loop-Driven Graphical Unitary Group Approach: A Powerful Method for the Variational Description of Electron Correlation , 1980 .

[24]  G. Diercksen,et al.  Ionization potentials of ethylene, allene and butatriene by a green function method , 1976 .

[25]  E. Davidson,et al.  Configuration interaction calculations on the planar 1(π,π*) state of ethylene , 1977 .

[26]  Robert J. Buenker,et al.  Configuration interaction calculations for the N2 molecule and its three lowest dissociation limits , 1977 .

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

[28]  S. Peyerimhoff,et al.  Ab initio calculations on the electronic spectrum of ethane , 1975 .

[29]  P. Löwdin.  Quantum Theory of Many-Particle Systems. I. Physical Interpretations by Means of Density Matrices, Natural Spin-Orbitals, and Convergence Problems in the Method of Configurational Interaction , 1955 .

[30]  M. Tinkham.  Group Theory and Quantum Mechanics , 1964 .

[31]  S. Peyerimhoff,et al.  A study of the convergence in iterative natural orbital procedures , 1977 .