Table 2 Equilibrium bond lengths and dissociation energies for the F molecule with a DZP + basis set." |

Table 2.1 Electronic contributions to binding energies, -AE i, of H-bonds of type H3Z—HX, calculated using DZP basis set at SCF level. Data in kcal/moF. |

Table 3.74 Frequency shifts and IR intensity enhancements of the two monomers in HCN—HCN complex. Data calculated at SCF level using DZP basis set . |

The results on tables 9 and 10 show that increasing the size of the cluster and/or the basis set does not change appreciably either the structure of the TS s or the activation energies obtained at a lower level of calculation (3T cluster and DZP basis set). Irrespective of the substrate and level of calculation employed, the results show that the protolytic cracking involves the attack of the zeolitic proton to a [Pg.68]

Table 4 also contains an analogous analysis of the saturated CH3—XH3 systems for X = C - Pb, for comparison purposes. The optimized geometries were taken from CAS (2,2) calculations on CH3—XH3 using the CEP-DZP basis set. VBSCF calculations were then carried out on the CH3—XH3 set using the usual 3 VB structures one covalent (CH3 XH3) and two ionic (CII3 XI[3 and CH3-XH3+)39. [Pg.9]

The atomic basis consists in a double-zeta set expanded with polarization functions (DZP) and augmented by diffuse functions (DZPR). Exponents and contraction coefficient are from McLean and Chandler 1980 [18] diffuse functions, centered on the heavy atoms with exponents of 0.023 for the s orbitals and 0.021 for the p orbitals are from Dunning and Hay 1977 [34]. Extension of the DZP basis set with two sets of diffuse s (0.0437, 0.0184) and p (0.0399, 0.0168) functions (DZPRR) has also been tested. [Pg.414]

Similar sorts of conclusions apply to the frequencies. A systematic study " found that a DZP basis set yields vibrational frequencies within about 9% of experimental (harmonic) values. The discrepancy diminishes to 4% when correlation is included via CISD and to 2% with a coupled cluster treatment. Another set of calculations confirmed the eost-effec-tiveness of the MP2 treatment of vibrational frequencies, indicating better agreement with experiment than MP3 on some oceasions. Certain types of modes can be more sensitive to the level of theoretical treatment than others. For example, out-of-plane bending motions for it-bonded systems can require triple- plus two sets of polarization functions, as well as a set of/-functions in the basis set . [Pg.143]

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