Ab initio calculations of vibrational unpolarized absorption and circular dichroism spectra of 6,8-dioxabicyclo[3.2.1] octane are reported. The harmonic force field is calculated via Density Functional Theory using three density functionals: LSDA, BLYP, B3LYP. The basis set is 6-31G*. Spectra calculated using the hybrid B3LYP functional give the best agreement with experimental spectra, demonstrating that this functional is superior in accuracy to the BLYP and LSDA functionals.
Large differences have been reported in previous SCF calculations of the NMR shielding tensor of the ethylenic carbon atom in tetrachlorocyclopropene. Our calculations show that these differences are due to the use of different molecular geometries, not to differences in the methods applied to obtain gauge-invariance.
Abstract The first‐order geometrical response equations for a state‐averaged multiconfigurational self‐consistent field ( SA ‐ MCSCF ) calculation are derived. This derivation is carried through from first principles to final working equations suited for computer implementation. The final equations are expressed such that the energies and wave functions must be known only for the internal SA ‐ MCSCF states. In the derivation, the special but important case where two or more internal states have equal weighting factors is treated in a manner fully consistent with all other cases. Except for introducing extra equations that are straightforward to solve, the case where two or more internal states have equal weighting factors introduces no new complications.
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