First principle calculations of dipole-dipole dispersion coefficients for the ground and first π → π* excited states of some azabenzenes

Issue title: Computational aspects of electric polarizability calculations: Atoms, Molecules and clusters, Part I

Article type: Research Article

Authors: Norman, Patrick^{; *} | Jiemchooroj, Auayporn | Sernelius, Bo E.

Affiliations: Department of Physics and Measurement Technology, Linköping University, SE-581 83 Linköping, Sweden

Correspondence: [*] Corresponding author. E-mail: panor@ifm.liu.se.

Abstract: The complex polarization propagator method has been applied to the calculation of dipole-dipole dispersion coefficients (also known as C6 coefficients) of pyridine, pyrazine, and s-tetrazine. These calculations refer to the electronic ground states as well as the first excited states of π→π∗ character. It is argued that accurate ground state dispersion coefficients are obtained with density functional theory using the B3LYP exchange-correlation functional. The proposed values for the C6 coefficients of pyridine, pyrazine, and s-tetrazine in their ground states are 1543 a.u., 1398 a.u., and 1014 a.u., respectively. Multi-configurational complete active space calculations are performed on these compounds in their respective π→π∗ excited state. The isotropic averages of the frequency-dependent polarizabilities are smaller in the excited states, but the effective frequencies defined in the London – van der Waals dispersion relation – are on the other hand larger.

DOI: 10.3233/JCM-2004-4309

Journal: Journal of Computational Methods in Sciences and Engineering, vol. 4, no. 3, pp. 321-332, 2004