Mariusz Klobukowski

Well-tempered Gaussian basis sets for the calculation of matrix Hartree—Fock wavefunctions

Abstract Gaussian basis sets leading to wavefunctions with atomic total energies within 1 m E h of the Hartree—Fock values were prepared using the well-tempered formula for atoms Ga through Rn.

The ab initio model potential method. Main group elements

In this paper we present the ab initio core model potential method, in which the Coulomb and exchange core operators Jc and Kc are represented as accurately as possible using adequate local and nonlocal potentials, and the valence basis set is optimized in atomic MP SCF calculations following the variational principle. Nonrelativistic model potential parameters and valence basis sets are presented for the main group elements from Li to Xe. The pilot SCF molecular calculations on the ground states of N2, P2, As2, Sb2, and CaO show a good agreement between all‐electron and model potential results, in particular the changes observed in molecular results due to improvements of the valence part of the all‐electron basis set are reproduced by the model potential calculations.

Well-tempered gaussian basis set expansions of Roothaan-Hartree-Fock atomic wavefunctions for lithium through mercury

Abstract Roothaan-Hartree-Fock atomic orbitals were expanded in terms of the optimized well-tempered Gaussian-type functions for atoms from lithium (Z = 3) to mercury (Z = 80).

Model potentials for molecular calculations. II. The spd‐MP set for transition metal atoms Sc through Hg

Model potential parameters and valence orbitals were generated for the transition metal atoms Sc through Hg. Only the nd and (n + 1)s valence electrons were treated explicitly and the effects of the remaining electrons were replaced by model potentials. For brevity they may be called sd‐MPs. Major relativistic effects were incorporated on the level of Cowan and Griffins quasirelativistic Hartree‐Fock (QRHF) method for the second and third transition metal atoms. The model potential parameters and valence orbitals were determined so as to reproduce the results of the numerical Hartree‐Fock reference calculations. The obtained valence orbitals have inner nodal structure. The model potential method can yield a balanced description of the s2dn–1, sdn, and dn + 1 configurations of the atoms. The polarization functions were also generated for the use in molecular calculations.

Model potentials for main group elements Li through Rn

Model potential (MP) parameters and valence basis sets were systematically determined for the main group elements Li through Rn. For alkali and alkaline-earth metal atoms, the outermost core (n−1)p electrons were treated explicitly together with the ns valence electrons. For the remaining atoms, only the valence ns and np electrons were treated explicitly. The major relativistic effects at the level of Cowan and Griffin’s quasi-relativistic Hartree–Fock method (QRHF) were incorporated in the MPs for all atoms heavier than Kr. The valence orbitals thus obtained have inner nodal structure. The reliability of the MP method was tested in calculations for X−, X, and X+ (X=Br, I, and At) at the SCF level and the results were compared with the corresponding values given by the numerical HF (or QRHF) calculations. Calculations that include electron correlation were done for X−, X, and X+ (X=Cl and Br) at the SDCI level and for As2 at the CASSCF and MRSDCI levels. These results were compared with those of all-elec...

Model potential study of the interactions in Ar2, Kr2 and Xe2 dimers

Model potential (MP) method is used in SCF and dispersion energy calculations of weak interactions in Ar2, Kr2 and Xe2 dimers. The calculated SCF interaction energies at van der Waals region are very close to the ones from the best available all-electron (AE) calculations. The performance of both Moller-Plesset (M-P) and Epstein-Nesbet (E-N) schemes of the dispersion energy calculation is studied. The SCF interaction energy augmented with the E-N dispersion energy agree quite well with experimental energies. |For the Xe2 dimer the relativistic effects are included on the level of Cowan and Griffins Relativistic Hartree-Fock (RHF) method and their influence on the total interaction energy in the van der Waals region is found to be quite substantial.

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.

Transition metal–noble gas bonding: the next frontier

Abstract Recently developed well-tempered model core potentials were reparameterized and used to study the interactions between the coinage metal monohalides and a heavier rare gas atom RgMX (Rg=Ar, Kr, Xe; M=Cu, Ag, Au; X=F, Cl). Geometries and binding energies were calculated for these systems at the MP2 level of theory in order to aid in spectroscopic identification of these compounds.

Quantum chemistry of confined systems: structure and vibronic spectra of a confined hydrogen molecule

Structure and spectral properties of the hydrogen molecule confined in a spherically symmetric harmonic oscillator potential were studied using the configuration interaction method. Increased strength of the confining potential exerts significant influence on the geometry of the molecule as well as on the vibronic transitions between the electronic ground and lowest excited singlet states. With increasing confinement strength the bond length shortens, the absorption and emission vibronic bands become blue-shifted, and the intensities of the lines change in consequence of the change in the number of vibrational levels accessible in the transition. The spectral changes are noticeable even for weak confinement potentials.

Well-tempered GTF basis sets for the atoms K through χe

Abstract Well-tempered GTF basis sets have been prepared for the atoms K (Z = 79) to χe (Z = 54). They are close to the Hartree-Fock solution and virtually saturated. The size of the basis sets is large but the number of disticnt exponent values remains relatively small.