Main Group Atoms and Dimers Studied with a New Relativistic ANO Basis Set

Abstract

New basis sets of the atomic natural orbital (ANO) type have been developed for the main group and rare gas atoms. The ANO's have been obtained from the average density matrix of the ground and lowest excited states of the atom, the positive and negative ions, and the dimer at its equilibrium geometry. Scalar relativistic effects are included through the use of a Douglas-Kroll Hamiltonian. Multiconfigurational wave functions have been used with dynamic correlation included using second-order perturbation theory (CASSCF/CASPT2). The basis sets are applied in calculations of ionization energies, electron affinities, and excitation energies for all atoms and the ground-state potentials for the dimers. These calculations include spin-orbit coupling using the RASSCF State Interaction (RASSI-SO) method. The spin-orbit splitting for the lowest atomic term is reproduced with an accuracy of better than 0.05 eV, except for row 5, where it is 0.15 eV. Ionization energies and electron affinities have an accuracy better than 0.2 eV, and atomic polarizabilities for the spherical atoms are computed with errors smaller than 2.5%. Computed bond energies for the dimers are accurate to better than 0.15 eV in most cases (the dimers for row 5 excluded).

A Nonorthogonal State-Interaction Approach for Matrix Product State Wave Functions

“…We employed all-electron ANO-RCC basis sets of TZP quality 103,104 along with the scalarrelativistic DKH2 Hamiltonian 105 and a Cholesky-decomposition (CD) of the two-electron repulsion integrals as implemented in Molcas 82 (keyword Cholesky in the integral mod- spectively. In all DMRG-SCF calculations, the number renormalized block states m was set to 1024 which is sufficient to yield results of CASSCF quality for the active orbital spaces considered.…”

Gaussian basis sets for molecular applications

“…The initial publication in this direction targeted the alkali and alkaline earth metals, [23] introduced scalar relativistic effects via the use of a Douglas-Kroll-Hess (DKH) Hamiltonian, [24,25] and substituted the CISD method with complete-active-space selfconsistent field (CASSCF) and complete-active-space secondorder perturbation theory (CASPT2). [26,27] The same design principles have since been used in the development of ANO-RCC sets for the main group elements (groups 13-18), [28] the transition metal elements [including spin-orbit (SO) effects], [29] and the actinides and lanthanides (again including SO effects). [30,31] The ANO-S, ANO-L, and ANO-RCC basis sets are the standard basis sets within the MOLCAS software.…”

Charge Transfer in Uranyl(VI) Halides [UO2X4]2− (X = F, Cl, Br, and I). A Quantum Chemical Study of the Absorption Spectra

“…On uranium we used a (26s23p17d13 f 5g3h) primitive basis contracted to a quadruple-ζ size [10s9p7d5 f 3g] 38 and on oxygen the (14s9p4d3 f 2g) primitive basis set contracted to a triple-ζ size [4s3p2d1 f ]. 39 For the halide ligands we also used ANO-RCC basis sets of both triple-ζ and quadruple-ζ quality; 39 20 and were obtained in the following crystals: Cs 2 NaYF 6 , 40 Cs 2 NaYCl 6 41 and Cs 2 NaYBr 6 . 41 The embedding potential for iodide ion was produced in this work, following the recipe for the AIMP method 31,32 in the NaI crystal.…”