We develop a static quantum embedding scheme that utilizes different levels of approximations to coupled cluster (CC) theory for an active fragment region and its environment. In this approach, we solve the local fragment problem using a high-level CC method and address the environment problem with a lower-level Møller–Plesset (MP) perturbative method combined with an efficient relaxation mechanism. We define a static renormalized interaction for the fragment problem with the quantities obtained from the low-level method. This method has been assessed for convergence with respect to the basis set size, fragment size, and other parameters. Using localized bonds as the active fragment, we report results for N=N bond breaking in azomethane and for the central C–C bond torsion in butadiene.

About the speaker

Avijit Shee is currently an Assistant Project Scientist at the University of California, Berkeley. His research primarily focuses on quantum embedding methods, including Green’s function-based and wave function-based approaches, and on developing first-principles quantum dynamics methods grounded in selected Configuration Interaction (CI) techniques. He holds a PhD from Université de Toulouse III (Paul Sabatier), France, and he completed his postdoctoral research at the University of Michigan (2017-2021), where he contributed to advancing Green’s function coupled cluster (GFCC) solvers for quantum embedding and explored relativistic GW methods.