TY - JOUR

T1 - Construction of complex STO-NG basis sets by the method of least squares and their applications

AU - Matsuzaki, Rei

AU - Asai, Shigeko

AU - McCurdy, C. William

AU - Yabushita, Satoshi

N1 - Funding Information:
Work by S.Y. was supported in part by Grantsin- Aid for Scientific Research and by the MEXT-Supported Program for the Strategic Research Foundation at Private Universities, 2009-2013. The computations were partly carried out using the computer facilities at the Research Center for Computational Science, Okazaki National Institutes. Work by CWM was supported through the Scientific Discovery through Advanced Computing (SciDAC) program funded by the US Department of Energy, Office of Science, Advanced Scientific Computing Research, and Basic Energy Sciences.
Publisher Copyright:
© 2014, Springer-Verlag Berlin Heidelberg.

PY - 2014/9/1

Y1 - 2014/9/1

N2 - Electronic resonance state energies and photoionization cross sections of atoms and molecules are calculated with the complex basis function method by using mixture of appropriate complex basis functions representing one-electron continuum orbitals and the usual real basis functions for the remaining bound state orbitals. The choice of complex basis functions has long been a central difficulty in such calculations. To address this challenge, we constructed complex Slater-type orbital represented by N-term Gaussian-type orbitals (cSTO-NG) basis sets using the method of least squares. Three expansion schemes are tested: (1) expansion in complex Gaussian-type orbitals, (2) expansion in real Gaussian-type orbitals, and (3) expansion in even-tempered real Gaussian-type orbitals. By extending the Shavitt–Karplus integral transform expression to cSTO functions, we have established a mathematical foundation for these expansions. To demonstrate the efficacy of this approach, we have applied these basis sets to the calculation of the lowest Feshbach resonance of H2 and the photoionization cross section of the He atom including autoionization features due to doubly excited states. These calculations produce acceptably accurate results compared with past calculations and experimental data in all cases examined here.

AB - Electronic resonance state energies and photoionization cross sections of atoms and molecules are calculated with the complex basis function method by using mixture of appropriate complex basis functions representing one-electron continuum orbitals and the usual real basis functions for the remaining bound state orbitals. The choice of complex basis functions has long been a central difficulty in such calculations. To address this challenge, we constructed complex Slater-type orbital represented by N-term Gaussian-type orbitals (cSTO-NG) basis sets using the method of least squares. Three expansion schemes are tested: (1) expansion in complex Gaussian-type orbitals, (2) expansion in real Gaussian-type orbitals, and (3) expansion in even-tempered real Gaussian-type orbitals. By extending the Shavitt–Karplus integral transform expression to cSTO functions, we have established a mathematical foundation for these expansions. To demonstrate the efficacy of this approach, we have applied these basis sets to the calculation of the lowest Feshbach resonance of H2 and the photoionization cross section of the He atom including autoionization features due to doubly excited states. These calculations produce acceptably accurate results compared with past calculations and experimental data in all cases examined here.

KW - Autoionization

KW - Complex basis function method

KW - Feshbach resonance

KW - Gaussian-type orbital

KW - Least squares fitting

KW - Slater-type orbital

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U2 - 10.1007/s00214-014-1521-6

DO - 10.1007/s00214-014-1521-6

M3 - Article

AN - SCOPUS:84923765282

SN - 1432-881X

VL - 133

SP - 1

EP - 12

JO - Theoretical Chemistry Accounts

JF - Theoretical Chemistry Accounts

IS - 9

M1 - 1521

ER -