Physical Chemistry Seminar – Brooke Bonar, Graduate Student

About the event

Title: Auxiliary Field Quantum Monte Carlo: Application to Actinide Thermochemistry

Abstract: Auxiliary field quantum Monte Carlo (AFQMC) offers solutions for longstanding limitations in thermochemical calculations of actinides. Coupled cluster methods have had great success in actinide thermochemical calculations where the system of interest is small and single referenced. However, these methods break down for actinides systems requiring a multideterminantal treatment. In addition, high order correlation energy corrections (beyond triple excitations) are often costly and infeasible. AFQMC is a stochastic method, which has the potential to alleviate these issues. AFQMC is specifically suited for multideterminantal wavefunctions. This work gives an overview of the AFQMC method and applies AFQMC to thorium and thorium oxide systems, with the goal of determining bond dissociation energies of thorium oxide and thorium dioxide. Preliminary comparisons to CCSD(T) results are presented. In addition, challenges in determining suitable trial wavefunctions will be discussed.