Accuracy Assessment of the ROHF-CCSD(T) Calculationsof Dipole Moments of Small Radicals

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Title:Accuracy Assessment of the ROHF-CCSD(T) Calculationsof Dipole Moments of Small Radicals
Creators:
Urban, Miroslav
Neogrády, Pavel
Raab, Juraj
Diercksen, Geerd H. F.
Journal or Publication Title:
Collection of Czechoslovak Chemical Communications, 63, 9, pp. 1409-1430
Uncontrolled Keywords:<i>Ab initio</i> calculations, ROHF, Radicals, Dipole moments, Spin-adaptation, CCSD(T)

Abstract

Dipole moments of a series of radicals, OH, NO, NS, SF, SO, PO, ClO, CN, LiO, NO<sub>2</sub>, and ClO<sub>2</sub> were calculated by the Coupled Cluster CCSD(T) method with the single determinant restricted open shell Hartree-Fock (ROHF) reference. For all molecules theoretical dipole moments were carefully compared to experimental values. The size and the quality of the basis set were systematically improved. Spin adaptation in the ROHF-CCSD(T) method, largest single and double excitation amplitudes and the <i>T</i><sub>1</sub> diagnostics were considered as indicators in the quality assessment of calculated dipole moments. For most molecules the accuracy within 0.01-0.03 D was readily obtained. For ClO and CN the spin adaptation was necessary - its contribution was as large as 0.03-0.045 D. Large deviation from experiment is observed for OH in its A<sup>2</sup>Σ<sup>+</sup> excited state (0.135 D) and especially for LiO in its <sup>2</sup>Π ground state (0.22 D). No indication of the failure of theoretical calculations was found which leads to the conclusion that, even if there is still a space for the improvement of theoretical calculations, experimental values should be reconsidered. <p>

Title:Accuracy Assessment of the ROHF-CCSD(T) Calculationsof Dipole Moments of Small Radicals
Creators:
Urban, Miroslav
Neogrády, Pavel
Raab, Juraj
Diercksen, Geerd H. F.
Uncontrolled Keywords:<i>Ab initio</i> calculations, ROHF, Radicals, Dipole moments, Spin-adaptation, CCSD(T)
Divisions:Life and Chemical Sciences > Institute of Organic Chemistry and Biochemistry > Collection of Czechoslovak Chemical Communications
Journal or Publication Title:Collection of Czechoslovak Chemical Communications
Volume:63
Number:9
Page Range:pp. 1409-1430
ISSN:0010-0765
E-ISSN:1212-6950
Publisher:Institute of Organic Chemistry and Biochemistry
Related URLs:
URLURL Type
http://dx.doi.org/10.1135/cccc19981409UNSPECIFIED
ID Code:1390
Item Type:Article
Deposited On:06 Feb 2009 17:09
Last Modified:06 Feb 2009 16:09

Citation

Urban, Miroslav; Neogrády, Pavel; Raab, Juraj; Diercksen, Geerd H. F. (1998) Accuracy Assessment of the ROHF-CCSD(T) Calculationsof Dipole Moments of Small Radicals. Collection of Czechoslovak Chemical Communications, 63 (9). pp. 1409-1430. ISSN 0010-0765

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