Energy-adjustedab initio pseudopotentials for the second and third row transition elements: Molecular test for M2 (M=Ag,Au) and MH (M=Ru,Os)

Summary Recently published nonrelativistic and quasirelativistic energy-adjustedab initio pseudopotentials representing the M^(Z–28)+ cores of the second row transition metal atoms and the M^(Z–60)+ cores of the third row transition metal atoms have been tested in SCF, CI(SD) and CEPA1 calculations of the spectroscopic constants (R _e ,D _e , and _e ) of the ground states of the neutral and singly charged silver and gold dimers, and in state averaged CASSCF and multi-reference CI(SD) calculations of the spectroscopic constants (R _e ,D _e , _e , _e , /R). Comparison is made with experimental and reliable theoretical data where available; in the case of the hydrides, additional calculations with pseudopotentials published by other groups have been made for comparison.     

Pseudopotential study of the rare earth monohydrides,monoxides and monofluorides

Nonrelativistic and quasirelativistic energy-adjusted pseudopotentials for fixed 4f subconfigurations of the rare earth elements La through Lu together with corresponding optimized valence basis sets have been used in SCF and CI(SD) calculations to determine the spectroscopic constants for the energetically low lying superconfigurations of the lanthanide monohydrides, monoxides and monofluorides. The experimentally observed trends in dissociation energies, bond lengths and vibrational frequencies for the ground states of the calculated superconfigurations of the monoxides and monofluorides are well reproduced. The results for the monohydrides are mainly predictions.     

Structure and stability of gold-substituted diborane, boranes, and borohydride ions

Pseudopotential ab initio calculations were performed for species of the type BH _n (AuPH₃) _m ^k , where n+m=3 or 4, and the charge k is −2,…,+1. Some derivatives of these and diaurated diboranes were also studied. The structural data agree well with the available experimental evidence. Factors affecting the stability of these systems, including the role of aurophilic attraction, are discussed. The singly charged anions and the diaurated diboranes are predicted to be the most stable members of these series. Received: 22 January 1999 / Accepted: 2 June 1999 / Published online: 4 October 1999     

Transferable Pair Potentials for Liquid Iron,Cobalt and Nickel

Effective inter-ionic pair potentials for liquid iron, cobalt and nickel are derived from second order pseudopotential perturbation theory with the transferable electron-ion potential of Fiolhais and co-workers which was originally developed for the solid state. The liquid structure is obtained by the thermodynamically self consistent liquid state theory, the variational modified hypernetted chain (VMHNC) approximation. It has been found that the calculated structural properties at the investigated thermodynamic states just above the melting point agree well with experiment. In this work we have determined the parameters of liquids Fe, Co and Ni for the universal choice of the evanescent core pseudopotentials of Fiolhais'. We have shown that this pseudopotential is transferable to the liquid state if used this parameterisation.     

Exciton and polaron properties in GaxIn1−xAs ternary mixed crystals

Based on the pseudopotential method under the virtual crystal approximation that takes into account the effect of compositional disorder, the electron and heavy-hole effective masses and the dielectric constants in Ga_xIn_1−xAs (0≤x≤1) have been calculated. The results are firstly used in the Wannier equation, which allowed the determination of the exciton reduced mass, binding energy and Bohr radius; then, the polaron properties have been investigated. In this respect, the Fröhlich coupling parameter, Debye temperature and polaron effective mass are calculated and their dependence on the Ga concentration is examined. For InAs and GaAs, our results are generally in reasonable agreement with the known data in the literature, while for compositions x in the range 0-1, our treatment represents the first theoretical predictions. It is found that the exciton and polaron properties for compositions 0<x<1 differ from those of the parent compounds suggesting thus more diverse opportunities to describe most exciton and polaron properties in ternary mixed crystals of interest.     

Pseudopotential study of lanthanum and lutetium dimers

Relativistic energy-consistent small-core lanthanide pseudopotentials of the Stuttgart–Bonn variety and extended valence basis sets have been used for the investigation of the dimers La₂ and Lu₂. It was found that the ground states for La₂ and Lu₂ are most likely ¹∑ _g ⁺ (σ _g ²π _u ⁴) and ³∑ _g ⁻ (4f ¹⁴4f ¹⁴σ _g ²σ _u ²π_u ²), respectively. The molecular constants including error bars were derived from multireference configuration interaction as well as coupled-cluster calculations, taking into account corrections for atomic spin–orbit splitting as well as possible basis set superposition errors. The theoretical values for La₂ (R _e=2.70±0.03 ?, D _e=2.31±0.13 eV, ω_e=186±13 cm⁻¹) show good agreement with the experimental binding energy (D _e=2.52±0.22 eV), but the experimental vibrational constant in an Ar matrix (ω_e=236±0.8 cm⁻¹) is significantly higher. For Lu₂ the theoretical values (R _e=3.07±0.03 ?, D _e=1.40±0.12 eV, ω_e=123±1 cm⁻¹) are in overall excellent agreement with experimental data (D _e=1.43±0.34 eV, ω_e=122± 1 cm⁻¹). The electronic structures of La₂ and Lu₂ are compared to those other lanthanide dimers and trends in the series are discussed. Received: 25 March 2002 / Accepted: 2 June 2002 / Published online: 21 August 2002     

Ab initio calculations with effective core potentials on trivalent lanthanide–terpyridine complexes

 The electronic structures of complexes of terpyridine (tpy) with trivalent lanthanides (Ln) were calculated using ab initio methods with effective core potentials at Hartree–Fock and post-Hartree–Fock levels of theory. The quasirelativistic large-core (with 4f electrons included in the core) pseudopotentials of the Stuttgart group were chosen for the Ln atoms. The variation of several properties of the Ln(tpy)³⁺ complexes was studied for the whole Ln series. It was shown that there was a monotonous variation for all properties (geometrical and energetic) along the Ln series, except for Mulliken charges on the metal atom. Calculations were performed on three complexes of known solid-state structure. The difference between experimental and calculated geometries is discussed; for all structures, it is found to be lower than 0.2 ?. In all cases, the relative order from one complex to another is conserved. Received: 13 September 1999 / Accepted: 3 February 2000 / Published online: 19 April 2000     

On the use of pseudopotentials in molecular calculations

A series of tests was performed of the Kahn-Goddard-Melius-Topiol pseudopotentials in view of their utilization with small contracted basis sets in molecular computations. The effects of inner-shell separability and of basis set contraction are underlined. The utilizability of Topiol's valence least-squares fitted Gaussian basis sets is studied.     

Quasirelativistic energy-consistent 5f-in-core pseudopotentials for trivalent actinide elements

Quasirelativistic energy-consistent 5f-in-core pseudopotentials modelling trivalent actinides, corresponding to a near-integral 5f ⁿ occupation (n = 0–14 for Ac–Lr), have been generated. Energy-optimized (6s5p4d), (7s6p5d), and (8s7p6d) primitive valence basis sets contracted to polarized double to quadruple zeta quality as well as 2f1g correlation functions have been derived. Corresponding smaller basis sets (4s4p3d), (5s5p4d), and (6s6p5d) suitable for calculations on actinide(III) ions in crystalline solids form subsets of these basis sets designed for calculations on neutral molecules. Results of Hartree–Fock test calculations for actinide(III) monohydrates and actinide trifluorides show a satisfactory agreement with corresponding calculations using 5f-in-valence pseudopotentials. Even in the beginning of the actinide series, where the 5f shell is relatively diffuse, only quite acceptable small deviations occur as long as the 5f-shell does not participate significantly in covalent bonding. Electronic Supplementary Material Supplementary material is available in the online version of this article at and is accessible for authorized users.     

Quasirelativistic energy-consistent 5f-in-core pseudopotentials for divalent and tetravalent actinide elements

Quasirelativistic energy-consistent 5f-in-core pseudopotentials modeling divalent (5f ⁿ⁺¹ occupation with n = 5–13 for Pu–No) respectively tetravalent (5f ^n-1 occupation with n = 1–9 for Th–Cf) actinides together with corresponding core-polarization potentials have been generated. Energy-optimized (6s5p4d) and (7s6p5d) valence basis sets as well as 2f1g correlation functions have been derived and contracted to polarized double, triple, and quadruple zeta quality. Corresponding smaller (4s4p) and (5s5p) respectively (4s4p3d) and (5s5p4d) basis sets suitable for calculations on actinide(II) respectively actinide(IV) ions in crystalline solids form subsets of these basis sets designed for calculations on molecules. Results of Hartree–Fock test calculations for actinide di- and tetrafluorides show a satisfactory agreement with calculations using 5f-in-valence pseudopotentials. Electronic Supplementary Material The online version of this article doi: contains supplementary material, which is available to authorized users.