Ab initio method development for mechanistic studies of charge transport

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Anna Krylov of the University of Southern California is supported by an award from the Theory, Models and Computational Methods program to develop predictive ab initio methods to characterize the electronic structure of ionized and electron-attached states in model systems, such as small clusters of nucleobases, DNA hairpins or similar systems. The proposed developments are based on the equation-of-motion coupled-cluster approach for ionization potentials (EOM-IP) and electron-attached (EOM-EA) systems, which is capable of describing multiple closely lying electronic states in an accurate, robust and efficient computational scheme The PI and her research group are (i) implementing properties and analytic gradient calculations for EOM-IP-CCSD using a Frozen Natural Orbitals (FNO) approach); (ii) implementing non-iterative triples corrections for the IP-CCSD and IP-CISD methods to improve accuracy of these methods; (iii) extending the FNO scheme to EOM-EA-CCSD energies and gradient calculations; (iv) implementing efficient calculations of Dyson orbitals and other inter-state properties to aid interpretation of the results and facilitate more direct comparisons with the experiments; and (v) parallelizing and redesigning the tensor library to take advantage of modern computer architecture.The Krylov group develops methods with the aim to study charge transport through molecular wires, which plays a central role in many important processes such as the radiative or oxidative damage in DNA, light harvesting, molecular electronics and solar energy applications. Software developed by this research group is made available to the community by being implemented in widely used software packages: Q-CHEM and SPARTAN.This award is supported partially by a co-funding arrangement with the Office of Cyberinfrastructure (OCI).