The CCSD(T) method - known as the gold-standard in quantum chemistry; computationally scales as the seventh power of the size of the system, and can be prohibitive for large molecules. As part of our efforts to reduce the computational cost of the CCSD(T) method yet retain its accuracy, we present a simple, efficient and user-friendly protocol to extrapolate to CCSD(T) energies in conjunction with MP2 energies. The method is based on the generalized connectivity-based hierarchy (CBH) � which was originally developed in the different context of theoretical thermochemistry. However, the realization that the broad ideas involved in theoretical thermochemistry are transferable to the area of fragment-based methods, enabled us to get accurate CCSD(T) energies for larger molecules at a significantly reduced cost. This presentation overall focuses on the effective merger of these two disparate frontiers in quantum chemistry, and how a new concept inspired by theoretical thermochemistry enormously reduces the total number as well as the computational expense of electronic structure calculations required in our fragment-based approach without any appreciable loss of accuracy.

Successfully merging theoretical thermochemistry with fragmentation-based methods in quantum chemistry: Accurate CCSD(T) energies at a significantly reduced computational cost

248th National Meeting (2014)

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