Quintuple zeta basis set

Optimization of auxiliary basis sets for RI-MP2 and RI-CC2 calculations Core-valence and quintuple-zeta basis sets for H to Ar and QZVPP basis sets for Li to Kr134... 

The formation of SO3 from HOSO2 has been indirectly observed experimentally (e.g., Gleason et al. 1987) and the results indicate that Equation (70) is a fast reaction. The reaction coordinate has been computed by Majumdar et al. (2000) using B3LYP with 6-3 lG(d,p), triple-, quadruple- and quintuple-zeta basis sets with diffuse basis functions. 

Dunning basis sets have names such as cc-pVnZ. This notation stands for correlation-consistent polarized valence -zeta. For a double zeta basis set, n is replaced by a D, for a triple zeta basis set, n is replaced by a T, for a quadruple zeta basis set, n is replaced by a Q, for a quintuple basis set we use a 5, and for a sextuple basis set we use a 6. When diffuse functions are included, an aug prefix is included in the name, as in aug-cc-pVTZ. The cc-pVTZ basis set generally has a performance similar to 6-311G(2df,p). A special feature of the Dimning basis sets is that they have been designed so the series DZ, TZ, QZ, 5Z, 6Z... systematically converges on the infinite basis set limit (27). This feature has been exploited in the... 

Rappe, Smedley and Goddard (1981) Stevens, Basch and Krauss (1984) Used for ECP (effective core potentitil) calculations Dunning s correlation consistent basis sets (double, triple, quadmple, quintuple and sextuple zeta respectively). Used for correlation ctilculations Woon and Dunning (1993)... 

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. 

The next step up in basis set size is a Triple Zeta (TZ). Such a basis contains three times as many functions as tire minimum basis, i.e. six s-functions and three p-functions for the first row elements. Some of the core orbitals may again be saved by only splitting the valence, producing a triple split valence basis set. Again the term TZ is used to cover both cases. The names Quadruple Zeta (QZ) and Quintuple Zeta (5Z, not QZ) for the next levels of basis sets are also used, but large sets are often given explicitly in terms of the number of basis functions of each type. 

In the present work, correlation consistent basis sets have been developed for the transition metal atoms Y and Hg using small-core quasirelativistic PPs, i.e., the ns and (nA)d valence electrons as well as the outer-core (nA)sp electrons are explicitly included in the calculations. This can greatly reduce the errors due to the PP approximation, and in particular the pseudo-orbitals in the valence region retain some nodal structure. Series of basis sets from double-through quintuple-zeta have been developed and are denoted as cc-pVwZ-PP (correlation consistent polarized valence with pseudopotentials). The methodology used in this work is described in Sec. II, while molecular benchmark calculations on YC, HgH, and Hg2 are given in Sec. III. Lastly, the results are summarized in Sec. IV. 

Examining the results given in these two tables, it is seen that, for this small molecule, very advanced calculations can be carried out. In the tables, all the methods employed have been introduced in the previous sections. For the basis sets, aug-cc-pVnZ stands for augmented correlation consistent polarized valence n zeta, with n = 2-5 referring to double, triple, quadruple, and quintuple, respectively. Clearly, these basis functions are specially designed for... 

Several different sizes of cc basis sets are available in terms of final number of contracted functions. These are known by their acronyms cc-pVDZ, cc-pVTZ, cc-pVQZ, cc-pV5Z and cc-pV6Z correlation consistent polarized Valence Double/Triple/Quadru-ple/Quintuple/Sextuple Zeta). The composition in terms of contracted and primitive (for the s- and p-part) functions is shown in Table 5.3. Note that each step up in terms of quality increases each type of basis function by one, and adds a new type of higher... 

Table 14 Dissociation Energies, (kcal mol ), for the Water Dimer from MP2 Calculations with the cc-pVnZ and aug-cc-pVnZ Basis Sets. Uncorrected as well as Counterpoise-corrected Results are Given. The Results with the Quintuple Zeta Sets are From RI-MP2 Calculations...

Table 8.18 contains a set of energies labelled extrapolated as well as a set of energies labelled R12 . The R12 energies, which have been obtained from explicitly correlated MP2 and CCSD calculations similar to the C1-R12 calculations in Section 7.3.2, should be close to the basis-set limit [27]. The extrapolated energies in Table 8.18 have been obtained from the quintuple- and sextuple-zeta energies using the extrapolation technique described in Section 8.4.3. 

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