ISSN:
1089-7690
Quelle:
AIP Digital Archive
Thema:
Physik
,
Chemie und Pharmazie
Notizen:
The F2 ground state potential curve has been computed near re by means of the MCSCF, CI(SD), MR-CI(SD) and the recently proposed CPF method. Extensive sets of polarization functions including up to five d sets, three f sets, and one g set have been used to study the convergence of the total energy of De, and re for these methods on basis set extension. SCF and MCSCF show a similar behavior and are practically converged on the 2d1f level. Convergence is much slower for methods which include external correlation, such as CI(SD), MR-CI(SD), CPF. The largest calculation performed—MR-CI(SD) for a [6 4 2 1] basis—included 280 076 configuration state functions, and yields De and re with an accuracy of 0.07 eV and 0.015 a.u. These remaining errors are attributed mainly to the neglect of g functions. The present results provide detailed information concerning the relative importance of polarization functions which can be ordered as: d(1)〉d(2)(approximately-greater-than)f(1)〉d(3) for SCF and MCSCF and d(1)〉f(1)(approximately-greater-than)d(2)〉g(1)(approximately-greater-than)f(2)(approximately-greater-than)d(3) for methods including external correlation.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1063/1.448464
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