You Osanai

Compact and efficient basis sets of s- and p-block elements for model core potential method

We propose compact and efficient valence-function sets for s- and p-block elements from Li to Rn to appropriately describe valence correlation in model core potential (MCP) calculations. The basis sets are generated by a combination of split MCP valence orbitals and correlating contracted Gaussian-type functions in a segmented form. We provide three types of basis sets. They are referred to as MCP-dzp, MCP-tzp, and MCP-qzp, since they have the quality comparable with all-electron correlation consistent basis sets, cc-pVDZ, cc-pVTZ, and cc-pVQZ, respectively, for lighter atoms. MCP calculations with the present basis sets give atomic correlation energies in good agreement with all-electron calculations. The present MCP basis sets systematically improve physical properties in atomic and molecular systems in a series of MCP-dzp, MCP-tzp, and MCP-qzp. Ionization potentials and electron affinities of halogen atoms as well as molecular spectroscopic constants calculated by the best MCP set are in good agreement with experimental values.

Valence and correlating basis sets for the second transition-metal atoms from Y to Cd

Contracted Gaussian-type function sets are developed for the valence 5s and 4d orbitals and for correlating functions of the second transition-metal atoms Y through Cd. A segmented contraction scheme is used for its compactness and efficiency. Contraction coefficients and exponents are determined by minimizing the deviation of the target function from the average of accurate atomic natural orbitals for the three lowest LS states arising from the 5s24d n-2, 5s1 4d n-1, and 5s0d n configurations. The present basis sets give a well balanced description for the three configurations at the Hartree—Fock level, and yield more than 97% of the atomic correlation energies predicted by accurate natural orbitals of the same size.

Relativistic correlating basis sets for the sixth-period d-block atoms from Lu to Hg

Contracted Gaussian-type function sets to describe valence correlation are developed for the sixth-period d-block atoms Lu through Hg. A segmented contraction scheme is employed for their compactness and efficiency. Contraction coefficients and exponents are determined by minimizing the deviation from accurate natural orbitals generated from configuration interaction calculations, in which relativistic effects are incorporated through the third-order Douglas-Kroll approximation. The present basis sets yield more than 99% of atomic correlation energies predicted by accurate natural orbital sets of the same size. Relativistic model core potential calculations with the present correlating sets give the spectroscopic constants of the AuH molecule in excellent agreement with experimental results.

Relativistic correlating basis sets for lanthanide atoms from Ce to Lu

Contracted Gaussian‐type function (CGTF) sets for the description of the 4f subshell correlation and of the 6s and 5d subshell correlation are developed for lanthanide atoms from Ce to Yb. Also prepared are basis sets for the 5d orbitals, which are vacant in the ground states of most lanthanide atoms but are essential in molecular environments. In addition, correlating CGTF sets for the 4f subshell correlation are supplemented for the Lu atom. A segmented contraction scheme is employed for their compactness and efficiency. Contraction coefficients and exponents are determined by minimizing the deviation from accurate natural orbitals generated from configuration interaction calculations that include relativistic effects through the third‐order Douglas–Kroll approximation. All‐electron and model core potential calculations with the present correlating sets are performed on the ground state of the diatomic CeO molecule. The calculated spectroscopic constants are in good agreement with experimental values.

Relativistic correlating basis sets for the main group elements from Cs to Ra

Contracted Gaussian-type function sets are developed for correlating functions of the ten main group elements from Cs to Ra. A segmented contraction scheme is used for its compactness and efficiency. Contraction coefficients and exponents are determined by minimizing the deviation from accurate natural orbitals or K-orbitals, incorporating the relativistic effect by the third-order Douglas–Kroll approximation. The present basis sets yield more than 98% of atomic correlation energies predicted by accurate natural orbitals of the same size. The use of the present set with the model core potential methods gives more than 99% of the correlation energies obtained by the atomic natural orbitals optimized for the model core potential itself. The present correlating sets applied to relativistic model core potential methods including spin–orbit effects predict the spectroscopic constants of the BiH molecule in excellent agreement with experimental results.

Revised model core potentials for first-row transition-metal atoms from Sc to Zn

We have developed new relativistic model core potentials (MCPs) for the first-row transition-metal atoms from Sc to Zn, in which 3s and 3p electrons are treated explicitly together with the 3d and 4s electrons. By adding suitable correlating functions, we demonstrated that the present MCP basis sets show reasonable performance in describing the electronic structures of atoms and molecules, bringing about accurate excitation energies for atoms and good molecular spectroscopic constants.

Relativistic correlating basis functions for the Ga–Kr, In–Xe, and Tl–Rn atoms

Generally contracted Gaussian-type function sets were developed for relativistic correlating functions of the Ga–Kr, In–Xe, and Tl–Rn atoms using an atomic natural orbital (ANO) approach. The ANOs were constructed based on configuration interaction calculations of the ground states of respective atoms including the major relativistic effects through model core potentials (MCPs). Both atomic and molecular applications are presented. The use of the present basis sets in conjunction with the MCPs gave the excitation energies, ionization potentials, and electron affinities in good agreement with the observed values for several atoms. The spectroscopic constants of the TlH molecule yielded by relativistic MCP calculations including spin–orbit effects were in excellent agreement with the experimental results.

Relativistic correlating basis sets for actinide atoms from 90Th to 103Lr

For 14 actinide atoms from 90Th to 103Lr, contracted Gaussian‐type function sets are developed for the description of correlations of the 5f, 6d, and 7s electrons. Basis sets for the 6d orbitals are also prepared, since the orbitals are important in molecular environments despite their vacancy in the ground state of some actinides. A segmented contraction scheme is employed for the compactness and efficiency. Contraction coefficients and exponents are so determined as to minimize the deviation from accurate natural orbitals of the lowest term arising from the 5fn−16d17s2 configuration. The spin‐free relativistic effects are considered through the third‐order Douglas‐Kroll approximation. To test the present correlating sets, all‐electron calculations are performed on the ground state of 90ThO molecule. The calculated spectroscopic constants are in excellent agreement with experimental values.

Theoretical determination of energies and widths of autoionizing states of the Be atom

The energy and width of the autoionizing state of the Be atom were calculated. A series of multireference configuration-interaction (MRCI) calculations with an extensive Slater-type function (STF) basis set was carried out and the full CI energy was estimated for each of the neutral and ionized states. The estimated energy of is with respect to the ionized state. The photoionization cross section from the state was calculated by using the R-matrix method. The resultant energy and width are and , respectively, in reasonable agreement with the observed values of and . The energies and widths of the series up to n = 11 were also calculated.