9523055472

Abstract

Nowdays, coupled cluster method belongs to one of the most used ąuantum Chemical methods. However, the single-reference coupled cluster methods are not able to describe Systems where the static correlation have an important role. Multireference coupled cluster methods developed in our group can describe both static and dynamie correlation and can be used for problematic Systems. Together with explicitly correlated wavefunction, which can properly describe the electronic cusp and speed up the con-vergence to the complete basis set limit, they are able to calculate computationally demanding diradicals. Multireference CC cal-culations of tetramethylenethane have been perforemd and the performance of explicitly correlated version is discussed. Calcu-lations of the isomerization of bicyclobutane using the multireference approach are presented as well.

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