DZ+P basis

Table 1 Calculations on HF with DZ+P basis. The total energies are reported as -(E + 99) hartree. Dimension should be understood as number of determinants (number of spin-adapted configurations in italics). NPE (non-parallelity error) is the difference between the maximal and minimal deviation from FCI...

Table 2 Same as Table 1 forHiO with DZ+P basis. The total energies are reported as -(E + 75) hartree... 

Kaupert, Heydtmann and Thiel"2 calculated the vibrational spectrum of monohalo-genated 1 at the HF level using the 6-31 G(d) basis set and effective core potentials with DZ + P basis sets for Cl, Br and I. Reduction from Z)3h to Cs symmetry leads to considerable coupling between modes (exceptions C—H stretching and CH2-deformation modes) of 1. Vibrational frequencies that are influenced by the halogen substituent are shifted to lower values with increasing mass of the halogen. 

Cometta-Morini, Ha and Oth246 have investigated the vibrational spectra of cyclopropyl and allyl radicals using DZ + P basis sets at the UHF and UMP2 level. Calculated harmonic... 

In the seventies and eighties, ab initio calculations on potentially homoaromatic molecules were preferentially carried out with the Hartree-Fock (HF) method using minimal or double-zeta (DZ) basis sets. However, neither HF nor small basis sets are appropriate to describe a homoaromatic system. In the case of cyclopropyl homoconjugation, the use of a DZ + P basis set is mandatory since polarization (P) functions are needed to describe the bond arrangements of a three-membered ring. 

Szabo, Kraka and Cremer have recently carried out an extensive ab initio investigation of 93 using MP2, MP3 and MP4 in conjugation with DZ+P basis, calculating chemical shifts and magnetic susceptibility and analyzing orbitals and electron density distribu-... 

The HF calculations predict a 3II ground state, which is the same as found for CaO, but as noted above, Cl might well reverse this ordering, and it is clear that very extensive calculations are needed before this question is definitely settled. A very recent paper reporting PE curves for BeO, MgO, and CaO, using DZ + P basis sets, has also appeared,310 and the authors also discuss the dissociation behaviour of the ground state. Calculation of the spin-orbit matrix elements shows that 3I1 and 12+ states are not significantly mixed. 

Theoretical work on the low-lying excited states has been confined to rather small calculations in the past,418>417 but a recent very detailed study using a GTO DZ + P basis set has appeared.418... 

The more extensive calculations of Bender and Schaefer,453 using a DZ + P basis set, evaluated both SCF and first-order wavefunctions. 252 configurations were included for the zBi state, and 387 for the Mi state. The computed bond lengths and other properties are given in Table 8. The 2i i-Mi splitting is predicted to be 1.67 eV from the best Cl calculation. The SCF wavefunction is a rather good approximation to the total wavefunction. 

Liskow602 et al. carried out SCF and Cl calculations, using their first-order wave-function technique, with an essentially DZ + P basis set. The computed values of... 

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