Sandipan Banerjee

A QM/MM approach for the study of monolayer-protected gold clusters

We report the development and implementation of hybrid methods that combine quantum mechanics (QM) with molecular mechanics (MM) to theoretically characterize thiolated gold clusters. We use, as training systems, structures such as Au25(SCH2–R)18 and Au38(SCH2–R)24, which can be readily compared with recent crystallographic data. We envision that such an approach will lead to an accurate description of key structural and electronic signatures at a fraction of the cost of a full quantum chemical treatment. As an example, we demonstrate that calculations of the 1H and 13C NMR shielding constants with our proposed QM/MM model maintain the qualitative features of a full DFT calculation, with an order-of-magnitude increase in computational efficiency.

Ab initio potential curves for the X2Σu+, A2Πu and B2Σg+ states of Ca2+

We report \textit{ab initio} calculations of the X

Ab initio potential curves for the X

^2 \Sigma_{u}^+

^2\Sigma_u^+

, A

, A

^2\Pi_u

^2\Pi_u

and B

and B

^2 \Sigma_{g}^+

^2\Sigma_g^+

states of the Ca

states of Ca

_{2}^+

_{2}^+

dimer. All electron CAS+MRCI calculations are performed for the X