Application of QCH Methods and Programs for Calculations of PES and Molecular Properties to Acctual Chemical Problems
1) Ab initio calculations of PES and transition dipole moments for modeling of ionic-rare gas clusters
a) Very accurate multireference configuration interaction calculation of the PES of the Kr3+ system with the inclusion of spin-orbit interaction by use of a two-step uncontracte determinantal effective Hamiltonian-based SO-CI method (EPCISO) of V. Valet et al, J.Chem. Phys. 113 (2000) 1391. The aim is to provide the complete manifold of states in the vicinity of the Rg3 cluster in order to enable experimental studies of vertical ionization of the Kr3 clusters.
b) Accurate calculation of PES of the ground and the two lowest excited states of He3+ systems at the whole range of internuclear configuration for building up the semiempirical models for larger Hen+ clusters. The test of the models by additional calcualtions for He4+ and He5+.
Methods: CCSD(T), multireference CI, use of the relativistic effective core potentials
F.X.Gadea, IRSAMC, Universite Paul Sabatier, Toulouse, France
Rene Kalus, Cluster Physics Group, University of Ostrava, Czech Republic
2) Ab initio linear response calculation of dipole electric polarizabilities and their derivatives
a) The dependence of static dipole properties on the internuclear distance in diatomic molecules for a wide range of internuclear distances. The electric dipole polarizability tensor is one of the crucial parameters in semi-empirical modeling of potential energy surfaces (PES) of polyatomic molecules which are necessary for molecular dynamic studies used in the interpretation of experiments.
b) Calculation of electric dipole polarizabity derivatives for CH4, C3H8 and C3H6 molecules. These derivatives are important characteristics of molecular potential in the inelastic collision processes.
c) Calculations of dynamic dipole polarizability tensors of HX, X=F,Cl, and Br for a set of 10 imaginary frequencies that allows to evalute C6 coefficients discribing dispersion forces for HX - HX complexes.
Single configuration linear response methods such as the second order polarization propagator approximation (SOPPA) the second order polarization propagator approximation with coupled cluster singles and doubles amplitudes - SOPPA(CCSD) or coupled cluster linear response theory (CCSD). Multiconfigurational self-consistent field (MCSCF) linear response calculations,
S. P. A. Sauer, Department of Chemistry, University of Copenhagen. Denmark