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A RASSCF calculation of NMR parameters

The next input file gives an example of the input needed for evaluating the two parameters determining an NMR spectrum, the nuclear shielding  constants and the spin-spin coupling constants . We do this at a fixed geometry, and use a Restricted Active Space (RAS)  wave function. In this way we include near degeneracy  effects by inclusion of the appropriate orbitals in the RAS2 space, and also some of the dynamical correlation  by single and double excitations from the RAS2 space (and generally also form the RAS1 space) into the RAS3 space.

In this input we once more use water  as input molecule, where we keep the 1s inactive, correlate 8 electrons in 6 orbitals (Full-Valence CAS) and in addition allow single- and double-excitations into 7 additional orbitals.

tabular480



Kenneth Ruud
Sat Apr 5 10:26:29 MET DST 1997