Treating Solutes and Protein Chromophores Properly: Polarizable Embedding with Correlated Wave Functions

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Electronic structures with large static and dynamical correlation effects pose a formidable challenge in modern quantum chemistry. Static correlation can be recovered using a complete active space (CAS) method where all possible configurations are considered for a pre-selected space of orbitals and electrons. However, the results are often non-quantitative due to the lacking description of dynamical correlation.
Furthermore, for chemical problems in solution and structured environments, both the nuclear dynamics and the electronic interactions between chromophore or solute and the environment become important.

To describe the static and dynamical correlation of a solute or protein chromophore efficiently and accurately, we have combined the CASSCF method with (short-range) density functional theory (srDFT) using a range-separation method (CAS-srDFT).
To include environment effects, we use a discrete mean-field embedding method that includes both electrostatic and polarization interactions. In this contribution, the formal equivalence to our new method and polarizable continuum methods (e.g.~COSMO or PCM) will be discussed. The importance of a discrete description of the environment in proteins as well as the importance of considering solvent dynamics will be demonstrated.

Finally, the most recent developments in range-separated methods will be highlighted: A srDFT method with a long-range wave function based on the Density Matrix Renormalization Group (DMRG-srDFT). This method allows us to extend the size of the active space considerably, and this has already been used in a few pilot applications for d-block transition metals.
Periode20. sep. 201524. sep. 2015
BegivenhedstitelSTC 2015 | Symposium on Theoretical Chemisty: Chemistry in Motion
PlaceringPotsdam, TysklandVis på kort