Basis sets cc-pVTZ

The DFT calculations were done with the deMon code [42] on a Cray C94. The set of auxihary basis functions is (3,4 3,4) for Pd and (4,4 4,4) for C and O [43], The orbital basis sets are Dunning s correlation-consistent Valence Triple-Zeta basis sets (cc-pVTZ) on C and O, and (2211/2111/121) for Pd [44], where only s-, p- and (six components) d-type functions were retained. The Pd atoms are treated as -i-16 electron atoms, using a... 

Fig. 3 Stationary points on the Br + H2O potential energy surface. Optimized geometrical parameters for the structures of the reactants, entrance complex, transition state, exit complex, and products from the CCSD(T) method with the relativistic basis sets cc-pVTZ-PP cc-...

Obtained from the CCSD(T) method with basis sets cc-pVTZ-PP and cc-pVQZ-PP, respectively. The column AZPVE reports the difference in ZPVE between reactants (Br -I- H2O) and the stationary point... 

Fig. 5 Left Equilibrium structures and equilibrium dissociation energies (in cm ) for complexes of CsH with L = N2 and CO2. CCSD(T)-F12a and a combination of the basis sets cc-pVTZ-F12 (C3H+) and aug-cc-pVQZ-F12 (ligands) was used. Right Infrared photodissociation (IRPD) spectra of L dimers recorded in the C3HJ fragment channel. The...

An informative study on excited states of diatomic molecules has been made by Sattelmeyer et al. [69], This study includes a comparison with FCI results as well as a comparison of some extended basis set CC values of re, coe, and Te with experimental data. A total of 7 valence excited states were studied BH (1n) CH+ (1I1) C2 ( u and 1FLU) CO (1I1) N2 Ilg and 1 ). First, for BH and CH+ CCSD, CC3, CCSDT-3, CCSDT, CCSDTQ, and FCI results were obtained with the cc-pVDZ basis set. Next, all molecules were studied with the CCSD, CC3, and CCSDT-3 methods and the cc-pVDZ, cc-pVTZ, cc-pVQZ, and cc-pV5Z basis sets. Diffuse functions were not included since the excited states considered are of valence character. 

The equilibrium geometries of all considered molecules were obtained in the previous study [108] at the all-electron CCSD(T) level in the correlation consistent core-valence triple- basis set (cc-pCVTZ) of Dunning [95] and Woon and Dunning [140]. For the hydrogens contained in the molecules, the cc-pVTZ basis set was used [95]. All the molecules are closed-shell species, therefore the RHF reference wave function was used as the reference for the geometry relaxation. The equilibrium structures are presented in Figures 8, 9, 10, 11 and 12. 

A series of basis sets developed in calculations which included electron correlation effects have been introduced by Dunning et al. " These basis sets are referred to as correlation-consistent polarized split-valence basis sets (cc-pVXZ, where X = D for double, T for triple, Q for quadruple, and 5 for quintuple-split). These basis sets have been systematically constructed to improve the description of the polarization space as the valence-space description is improved. They have also been augmented with diffuse functions (aug-cc-pVXZ), with a set of diffuse functions added for each value of the quantum number t which appears in the original basis set. (For example, the cc-pVTZ basis set has three sets of valence-space functions, two sets of functions in the first polarization space, and a single set of functions in the second polarization space. For a second-period element, this translates to a single s orbital for the inner shell, three sets of s and p orbitals in the valence shell, and two sets of d and a set of f orbitals in the polarization space. The aug-cc-pVTZ basis set includes an additional set of diffuse s, p, d, and f orbitals.) Because... 

Electron correlation studies demand basis sets that are capable of very high accuracy, and the 6-31IG set I used for the examples above is not truly adequate. A number of basis sets have been carefully designed for correlation studies, for example the correlation consistent basis sets of Dunning. These go by the acronyms cc-pVDZ, cc-pVTZ, cc-pVQZ, cc-pV5Z and cc-pV6Z (double, triple, quadruple, quintuple and sextuple-zeta respectively). They include polarization functions by definition, and (for example) the cc-pV6Z set consists of 8. 6p, 4d, 3f, 2g and Ih basis functions. 

I have included some representative results in the table, using the cc-pVTZ basis set. 

A+B L -fl/2) have also been used. The theoretical assumption underlying an inverse power dependence is that the basis set is saturated in the radial part (e.g. the cc-pVTZ ba.sis is complete in the s-, p-, d- and f-function spaces). This is not the case for the correlation consistent basis sets, even for the cc-pV6Z basis the errors due to insuficient numbers of s- to i-functions is comparable to that from neglect of functions with angular moment higher than i-functions. 

We will now look at how different types of wave functions behave when the O-H bond is stretched. The basis set used in all cases is the aug-cc-pVTZ, and the reference curve is taken as the [8, 8J-CASSCF result, which is slightly larger than a full-valence Cl. As mentioned in Section 4.6, this allows a correct dissociation, and since all the valence electrons are correlated, it will generate a curve close to the full Cl limit. The bond dissociation energy calculated at this level is 122.1 kcaPmol, which is comparable to the experimental value of 125.9 kcal/mol. 

From a basis set study at the CCSD level for the static hyperpolarizability we concluded in Ref. [45] that the d-aug-cc-pVQZ results for 7o is converged within 1 - 2% to the CCSD basis set limit. The small variations for the A, B and B coefficients between the two triple zeta basis sets and the d-aug-cc-pVQZ basis, listed in Table 4, indicate that also for the first dispersion coefficients the remaining basis set error in d-aug-cc-pVQZ basis is only of the order of 1 - 2%. This corroborates that the results for the frequency-dependent hyperpolarizabilities obtained in Ref. [45] by a combination of the static d-aug-cc-pVQZ hyperpolarizability with dispersion curves calculated using the smaller t-aug-cc-pVTZ basis set are close to the CCSD basis set limit. 

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