Pseudopotentials , correlation consistent basis sets

Peterson, K.A. and Puzzarini, C. (2005) Systematically convergent basis sets for transition metals. II. Pseudopotential-based correlation consistent basis sets for the group 11 (Cu, Ag, Au) and 12 (Zn, Cd, Hg) elements. Theoretical Chemistry Accounts, 114, 283-296. 

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. 

New correlation consistent basis sets have been developed for Y and Hg in conjunction with accurate small-core relativistic pseudopotentials. A few allelectron basis sets have also been optimized both with and without the inclusion... 

Another recent set of pseudopotentials for the 4p, 5p, and 6p elements has been developed by Dyall (1998, 2002). These ECPs are designed to be the ECP-equivalent to the correlation-consistent basis sets of Dunning insofar as (i) prescriptions for double- and... 

As an alternative to all-electron calculations using either 4-component or DKH calculations, relativistic pseudopotentials (PPs) or effective core potentials (ECPs) provide a very convenient route to accurately including relativistic effects into electronic structure calculations [38,39]. Since PPs replace the low-lying core electrons, their use also results in smaller basis sets. Correlation consistent basis sets... 

Peterson, K.A. SystematicaUy convergent basis sets with relativistic pseudopotentials. I. Correlation consistent basis sets for the post-d group 13-15 elements, J. Chem. Phys. 2003,119,11099. 

Peterson, K.A., Dolg, M., Stoll, H. Energy-consistent relativistic pseudopotentials and correlation consistent basis sets for the 3d elements Sc-Ni, in preparation. 

Other, scalar relativistic effects are usually minor. Among them, the most important is the contraction of s-orbitals caused by the increase in electron mass due to high velocity near the nucleus. Except in the most careful work, such effects are modeled using relativistic effective core potentials (ECPs), also called core pseudopotentials [76]. When an ECP is used, the corresponding valence basis set should be used for the remaining electrons. A small-core ECP, in which fewer electrons are replaced by the effective potential, is a weaker approximation and therefore more reliable than the corresponding large-core ECP. The selection of basis sets to accompany ECPs is more restricted than the selection of all-electron basis sets, but appropriate correlation-consistent basis sets are available for heavy p-block elements [77-80]. 

Peterson KA, Figgen D, Dolg M, and Stoll H. 2007. Energy-consistent relativistic pseudopotentials and correlation consistent basis sets for the 4d elements Y-Pd. J. Chem. Phys. 126, 124101 b) Figgen D, Peterson KA, Dolg M, StoU H. 2009. Energy-consistent pseudopotentials and correlation consistent basis sets for the 5d elements Hf-Pt. J. Chem. Phys. 130, 164108. 

Figgen D, Peterson KA, Dolg M, Stoll H. Energy-consistent pseudopotentials and correlation consistent basis sets for the 5d elements Hf-Pt. J Chem Phys. 2009 130 164108. 

Peterson KA, Yousaf KE. Molecular core-valence correlation effects involving the post-d elements Ga-Rn Benchmarks and new pseudopotential-based correlation consistent basis sets. J Chem Phys. 2010 133 174116. 

Stuttgart pseudopotential for Au with a uncontracted (lls/10p/7d/5f) valence basis set and a Dunning augmented correlation consistent valence triple-zeta sets (aug-cc-pVTZ) for both C and N, but with the most diffuse f function removed, was used. 

As an example for the typical quality of molecular properties obtained with the newly developed basis sets of Martin and Sundermann [241] the results for the energy-consistent large-core Ge pseudopotential for the diatomics GeH, GeO and GeF is displayed in Table 8. In addition to their work on main group PP basis sets Martin and Sundermann [241] also proposed (2flg) correlation sets to be used with the (8s7p6d)/[5s4p3d] valence basis sets of the transition... 

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