Abstract

New correlation consistent basis sets for the group 11 (Cu, Ag, Au) and 12 (Zn, Cd, Hg) elements have been developed specifically for use in explicitly correlated F12 calculations. This includes orbital basis sets for valence only (cc-pVnZ-PP-F12, n = D, T, Q) and outer core-valence (cc-pCVnZ-PP-F12) correlation, along with both of these augmented with additional high angular momentum diffuse functions. Matching auxiliary basis sets required for density fitting and resolution-of-the-identity approaches to conventional and F12 integrals have also been optimized. All of the basis sets are to be used in conjunction with small-core relativistic pseudopotentials [Figgen et al., Chem. Phys. 311, 227 (2005)]. The accuracy of the basis sets is determined through benchmark calculation at the explicitly correlated coupled-cluster level of theory for various properties of atoms and diatomic molecules. The convergence of the properties with respect to the basis set is dramatically improved compared to conventional coupled-cluster calculations, with cc-pVTZ-PP-F12 results close to conventional estimates of the complete basis set limit. The patterns of convergence are also greatly improved compared to those observed from the use of conventional correlation consistent basis sets in F12 calculations.

Highlights

  • The development of practical explicitly correlated methods in electronic structure theory has meant that accurate energies, structures, and properties of small-to medium-sized molecules can be obtained at a significantly reduced computational cost

  • While standard one-particle basis sets, such as the correlation consistent family,14 can be used in explicitly correlated methods, it has been shown that Gaussian basis sets developed for use in F12 approaches offer a number of advantages

  • Correlation consistent basis sets for the group (Cu, Ag, Au) and (Zn, Cd, Hg) elements have been developed for use in explicitly correlated F12 calculations based on the small-core relativistic PPs of Figgen et al

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Summary

INTRODUCTION

The development of practical explicitly correlated methods in electronic structure theory has meant that accurate energies, structures, and properties of small-to medium-sized molecules can be obtained at a significantly reduced computational cost Their slow convergence with respect to the one-particle basis set used to describe atomic/molecular orbitals meant that large basis sets needed to be used, often in conjunction with extrapolation procedures to estimate a complete basis set (CBS) limit.. While standard one-particle basis sets, such as the correlation consistent family, can be used in explicitly correlated methods, it has been shown that Gaussian basis sets developed for use in F12 approaches offer a number of advantages This has led to the design and optimization of cc-pVnZ-F12 basis sets for the elements H–Ar15–17 and cc-pVnZ-PP-F12 basis sets paired to pseudopotentials (PP) for the post-d main group elements Ga–Rn..

GENERAL COMPUTATIONAL DETAILS
Atomic orbital basis sets
Density fitting auxiliary basis sets
Complementary auxiliary basis sets
Choice of geminal exponent
Atomic properties
Molecular benchmark calculations
Method
CONCLUSIONS
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