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Dyall K.G.,Dirac Solutions Inc.
Journal of Chemical Physics | Year: 2013

A spectral representation of the self-energy based on hydrogenic atomic data is examined for its usefulness to evaluate the self-energy of many-electron atoms, and thus its potential for molecular calculations. Use of the limited hydrogenic data with a diagonal projection overestimates the valence self-energy by an order of magnitude. The same diagonal projection for the vacuum polarization produces a similar overestimate, but a full projection produces values that are within a factor of 2 of the exact value, as does a density-fitting procedure. © 2013 AIP Publishing LLC. Source


Dyall K.G.,Dirac Solutions Inc.
Theoretical Chemistry Accounts | Year: 2016

Relativistic basis sets of double-zeta, triple-zeta, and quadruple-zeta quality have been optimized at the self-consistent field level with a Gaussian nuclear charge distribution for the light elements H–Ar. Correlating functions were optimized for all shells in MR-CISD calculations on the ground configuration. Energies and properties evaluated with the basis sets are compared with those produced by several other basis sets. Prescriptions are given for constructing contracted basis sets. The basis sets are available as an internet archive. © 2016, Springer-Verlag Berlin Heidelberg. Source


Relativistic basis sets of double-zeta, triple-zeta, and quadruple-zeta quality have been optimized for the 7p elements at the Dirac-Coulomb self-consistent field level of theory with a Gaussian nuclear charge distribution. For all of these sets, valence and outer-core correlating functions have been optimized in multireference CI calculations on the valence p n states. Diffuse functions are also provided. Prescriptions are given for constructing contracted basis sets, based on MRCI calculations for correlation of the atoms. The basis sets are applied to a range of atomic and molecular properties, to provide information on how to use the basis sets. Tests of the basis sets with an explicit representation of the 8s showed that the 8s is not needed. The basis sets are available as an internet archive and from the Dirac program web site, http://dirac. chem. sdu. dk. © 2012 Springer-Verlag. Source


Dyall K.G.,Dirac Solutions Inc.
Theoretical Chemistry Accounts | Year: 2012

Gaussian functions for correlation of all core shells of elements from Z = 31 to Z = 118 have been optimized in relativistic singles and doubles CI calculations, performed on the shell of highest angular momentum for each principal quantum number. The SCF functions were derived from the double-zeta, triple-zeta, and quadruple-zeta basis sets previously optimized by the author. Only those Gaussian functions that are not represented in the SCF basis sets were optimized. The functions are available from the Dirac program web site, http://dirac. chem. sdu. dk. © 2012 Springer-Verlag. Source


Dyall K.G.,Dirac Solutions Inc.
Chemical Physics | Year: 2012

The kinetic balance criterion used in current relativistic basis set codes is satisfied by the electron solutions of the Dirac equation, but not the positron solutions. A proposal for applying kinetic balance to both sets of solutions is presented. The method is applied along with "normal" kinetic balance to one-electron systems, to investigate its possible relation to prolapse, and to the positron affinity of F -, to investigate the kinetic energy deficiency for positron solutions. The new method reduces but does not eliminate prolapse for energy-optimized basis sets, and provides faster and smoother convergence with basis set size for the positron affinity. © 2011 Elsevier B.V. All rights reserved. Source

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