There are a lot of interesting problems in surface chemistry where quantum chemistry could give great insight, like reaction mechanisms in heterogeneous catalysis, the effect of surface functionalization on semiconductors, or the influence of defects on the reactivity of crystal surfaces. Plane-wave methods applied to crystals cannot handle chemical problems that are localized in nature like surface defects and adsorbates. On the other hand, molecular electronic structure techniques, which describe these effects and the locality of the electronic correlation well, are too computationally expensive to use on these systems. A new approach based on coupled-cluster (CC) theory is proposed. This scheme reformulates the electronic amplitude equations to incorporate the periodicity of crystals and the locality of electronic interaction. This avoids the calculation of redundant amplitudes. Perfectly periodic surfaces are envisioned as reference wavefunctions for localized defects and chemical reactions. The working equations are derived starting from the amplitude equations of conventional CC on an infinite system and rearranging them such that the index displacement to a single “anonymous” cell is an explicit degree of freedom. The formally infinite number of equations, and the summation therein, can be truncated by systematically neglecting numerically insignificant amplitudes. The theory and the details of the computer implementation will be presented, as well as first tests of the equations on 1-dimensional electronic systems.

Translationally transformed coupled-cluster (TT-CC) theory in a local basis for periodic systems

2019 Fall National Meeting

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