Core - valence correlation effects in the ground and low - lying excited states of GaN

Michal Kraus (1) , Lucia Šimová (1) , Pavel Neogrády (1) , Miroslav Urban (2, 1)

1 Department of Physical and Theoretical Chemistry [Bratislava]
2 Institute of Materials Science

We present careful analysis of the accuracy of molecular properties of the GaN molecule calculated by the Coupled Cluster CCSD(T) method including the core-valence correlation effects. We demonstrate that calculations of the core-valence correlation effects with basis sets which were optimized considering just valence electrons of the gallium atom lead to unreliable results. Our objective is finding the relation between the accuracy and the oversimplification due to the use of aug-cc-pVXZ basis sets when 3d and eventually also 3s3p electrons are correlated with these basis sets, having in mind calculations of larger systems. We observe the oscillatory behavior of molecular properties with increasing cardinal basis set number X in the aug-cc-pVXZ series. This is main deficiency of this more economical basis set. Extrapolation to the complete basis set limit with this series is only possible starting with the aug-cc-pVQZ basis. Regular behavior with increasing X show results with the aug-cc-pCVXZ series. Reasonable molecular properties are provided by the ANO-RCC basis sets with 3d104s24p1 correlated electrons of Ga.

Mots clés: Physical Sciences

Michal Kraus, Lucia Šimová, Pavel Neogrády, Miroslav Urban. Core - valence correlation effects in the ground and low - lying excited states of GaN. Molecular Physics, 2010, 108 (03-04), pp.467-476. ⟨10.1080/00268970903563477⟩. ⟨hal-00580679⟩