F.E. Jorge

Accurate universal Gaussian basis set for all atoms of the Periodic Table

We have applied a discretized version of the generator coordinate Hartree–Fock method to generate a universal Gaussian basis set for the atoms from H through Lr. In general, for He to Rn the ground state Hartree–Fock total energy results obtained with our universal Gaussian basis set are lower than the corresponding ones obtained by Clementi et al. using larger atom-optimized geometrical Gaussian basis sets. For the atoms from H through Lr we have obtained ground state energy values with at least seven digits of accuracy (except for Pm, with six digits), in comparison with the corresponding ten digits of the numerical Hartree–Fock total energy results.

Contracted Gaussian basis sets for Douglas-Kroll-Hess calculations : Estimating scalar relativistic effects of some atomic and molecular properties

Douglas-Kroll-Hess (DKH) contracted Gaussian basis sets of double, triple, and quadruple zeta valence qualities plus polarization functions (XZP, X=D, T, and Q, respectively) for the atoms H-Ar and DZP and TZP for K-Kr are presented. They have been determined from the corresponding nonrelativistic basis sets generated previously by Jorge et al. We have recontracted the original XZP basis sets, i.e., the values of the contraction coefficients were reoptimized using the relativistic DKH Hamiltonian. The effect of DKH at the coupled-cluster level of theory on the ionization energy of some atoms and dissociation energy and geometric parameters for a sample of molecules is discussed. Our results were compared with theoretical and experimental values reported in the literature.

Gaussian basis sets of triple and quadruple zeta valence quality for correlated wave functions

Contracted basis sets of triple and quadruple zeta (TZ and QZ, respectively) valence quality for the atoms from H to Ar are presented. They have been determined from fully-optimized basis sets of primitive Gaussian-type functions generated in atomic Hartree–Fock (HF) calculations. Sets of Gaussian polarization functions optimized at the Møller–Plesset second-order (MP2) level were added to the TZ and QZ basis sets. This extends earlier work on segmented contracted double zeta valence basis sets. The performance of the basis sets are assessed in molecular HF and MP2 calculations for a sample of diatomic molecules by a comparison of energies, dissociation energies, and dipole moments with results obtained numerically or using basis sets reported in the literature. By fitting the directly calculated values through two extrapolation schemes, estimates of the complete basis set limit for second order correlation energy have been obtained. In addition, results for MP2-R12/A calculations to establish the basis set convergence for the standard calculations are also presented.

Gaussian basis set of double zeta quality for atoms Rb through Xe: application in non-relativistic and relativistic calculations of atomic and molecular properties

The all-electron contracted Gaussian basis set of double zeta valence quality plus polarization functions (DZP) for the atoms from Rb to Xe is presented. The Douglas–Kroll–Hess (DKH) basis set for fourth-row elements is also reported. The original DZP basis set has been recontracted, i.e. the values of the contraction coefficients were re-optimized using the relativistic DKH Hamiltonian. This extends earlier works on segmented contracted DZ basis set for atoms H-Kr. These sets along with ab initio methods were used to calculate ionization energies of some atoms and spectroscopic constants of a sample of molecules and, then, comparison with results obtained with other basis sets was made. It was shown that experimental and benchmark bond lengths and harmonic vibrational frequencies can be reproduced satisfactorily with DZP-DKZ.

Gaussian basis set of double zeta quality for atoms K through Kr: application in DFT calculations of molecular properties.

Contracted basis sets of double zeta (DZ) quality for the atoms from K to Kr are presented. They were determined from fully optimized basis sets of primitive Gaussian‐type functions generated in atomic Hartree‐Fock calculations. Sets of Gaussian polarization functions optimized at the Möller‐Plesset second‐order level were added to the DZ basis set. This extends earlier work on segmented contracted DZ basis set for atoms H‐Ar. From this set, using the BP86 nonhybrid and B3LYP hybrid functionals, dissociation energy, geometric parameters, harmonic vibrational frequency, and electric dipole moment of a set of molecules were calculated and compared with results obtained with other basis sets and with experimental data reported in the literature. In addition, 57Fe and 77Se nuclear magnetic resonance chemical shifts in Fe(C5H5)2, H2Se, and CSe2 were calculated using density functional theory and gauge‐including atomic orbitals and, then, compared with theoretical and experimental values previously published in the literature. Except for chemical shift, one verifies that our results give the best agreement with experimental and benchmark values.

Improved generator coordinate Hartree–Fock method: application to first-row atoms

Abstract An improved generator coordinate Hartree–Fock (IGCHF) method is proposed as a useful generalization of the generator coordinate Hartree–Fock (GCHF) method. The IGCHF uses two or three sets of basis functions for each symmetry. The two and three sets of exponents are generated from two and three different arithmetic sequences, respectively. Ground state Hartree–Fock calculations for first-row atoms using optimized Gaussian basis sets of the same size, generated with the GCHF and IGCHF methods, are carried out to demonstrate the substantial improvement offered by the IGCHF method.

Accurate universal Gaussian basis set for hydrogen through lanthanum generated with the generator coordinate Hartree-Fock method

Abstract The generator coordinate Hartree-Fock method is applied to generate an accurate universal Gaussian basis set for the atoms H ( Z = 1) through La ( Z = 57). The Hartree-Fock energy results obtained with our universal Gaussian basis set are compared with numerical Hartree-Fock results and with Hartree-Fock energy results obtained by using optimized Gaussian basis sets. For the atoms B through Ca we have obtained, when compared to the corresponding numerical Hartree-Fock results, an energy value within the accuracy of 10 −5 –10 −4 E h , and for Sc through La this accuracy lies between 10 −4 and 10 −3 E h . The universal Gaussian basis set presented in this work is generated taking into account the sharing of exponential functions between all s, p and d atomic orbitals, i.e. the shell constraint.

Gaussian basis set of triple zeta valence quality for the atoms from K to Kr: Application in DFT and CCSD(T) calculations of molecular properties

A contracted basis set of triple zeta (TZ) valence quality for the atoms from K to Kr was constructed from fully-optimized Gaussian basis sets generated in this work. Gaussian polarization functions (d, f, and g symmetries), which were optimized at the second-order Mφller–Plesset level, were added to the TZ set. This extends earlier work on segmented contracted TZ basis set for atoms H-Ar. This set along with the BP86 non-hybrid and B3LYP hybrid functionals were used to calculate geometric parameters, dissociation energy, harmonic vibrational frequency, and electric dipole moment of a sample of molecules and, then, comparison with results obtained with other basis sets and with experimental data reported in the literature is done. CCSD(T) atomic excitation energies and bond lengths, dissociation energies, and harmonic vibrational frequencies of some diatomics were also evaluated. Using density functional theory and gauge-including atomic orbitals, 57Fe and 77Se nuclear magnetic resonance chemical shifts in Fe(C5H5)2, H2Se, (CH3)SeH, CSe2, SeCO, H2CSe, and SeF6 were calculated. Comparison with theoretical and experimental values previously published in the literature was done. It is verified that in general these results give good agreement with experimental and benchmark values.

Triple zeta quality basis sets for atoms Rb through Xe: application in CCSD(T) atomic and molecular property calculations

Segmented all-electron contracted triple zeta valence plus polarization function (TZP) basis sets for the elements from Rb to Xe were constructed to be used in conjunction with the non-relativistic and Douglas–Kroll–Hess (DKH) Hamiltonians. This extends earlier work on segmented contracted TZ basis set for the atoms H-Kr. At the coupled cluster level of theory, ionization energy of some atoms as well as spectroscopic constants of a sample of diatomics were calculated and compared with benchmark theoretical values. One verifies that the benchmark bond length, dissociation energy, and harmonic vibrational frequency can be reproduced well with the TZP-DKZ set.

Accurate adapted Gaussian basis sets for the atoms from H through Xe

The authors have applied the generator coordinate Hartree-Fock method to generate adapted Gaussian basis sets for the atoms from H through Xe. The Griffin-Hill-Wheeler-Hartree-Fock equations are integrated numerically generating accurate basis sets for these atoms. The atomic wave functions are an improvement over those of Clementi et al. using larger atom-optimized geometrical Gaussian basis sets and Jorge et al. using a universal Gaussian basis set. In all cases, the current wave functions predict total energy results within 6.13 {times} 10{sup {minus}4} hartree of the numerical Hartree-Fock limit.