Aug-cc-pVDZ

An extension of this last notation is aug—cc—pVDZ. The aug denotes that this is an augmented basis (diffuse functions are included). The cc denotes that this is a correlation-consistent basis, meaning that the functions were optimized for best performance with correlated calculations. The p denotes... 

CCSD(T)/aug-cc-pVDZ Atomization energy 18 kcal/mol mean abs. dev. 

Table 1 Coefficients for 7[ (a ) for third harmonic generation (THG), degenerate four wave mixing (DFWM), electric field induced second harmonic generation (ESHG), and Kerr effect in methane at the experimental geometry rcH = 2.052 a.u. A CCSD wavefunction and the t-aug-cc-pVDZ basis were used. (Results given in atomic units, the number in parentheses indicate powers of ten.)...

Table 2 Convergence of the Taylor series and the series of diagonal Fade approximants (CCSD response, t-aug-cc-pVDZ basis). The inifinite order results were calculated using the implementation for the frequency-dependent response function.

Computations at the level of CCSD(T)/(aug-)cc-pVTZ are, however, very much time consuming and in the following instanton calculations the best level of theory employed is CCSD(T)/(aug-)cc-pVDZ. 

Figure 13. Comparison of the ab initio instanton trajectory by the CCSD(T)/(aug-)cc-pVDZ method with those obtained by (b) the global MP2 method and (c) analytic potential energy function.

Figure 15, Iterative calculation of the instanton path. The labels 1-9 show gradual improvement of the instanton trajectory shape using the MP2/cc-pVDZ ab initio data. After switching to the CCSD(T)/(aug-)cc-pVDZ ab initio method, only two more steps needed to achieve convergence and obtain the final results. Taken from Ref. [104].

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