Spin-orbit and relativistic all-electron potential energy curves for the ground and low-lying excited states of AgAu.

The spin-free and spin-orbit potential energy curves of ground and excited states of AgAu up to 5 eV have been investigated. Calculations have been performed at the all-electron level with scalar relativistic effects included through the second-order Douglas-Kroll-Hess Hamiltonian. We have used the complete active space multi-configuration self-consistent field method, followed by the multi-reference configuration interaction (MRCI) calculations. Energetics and spectroscopic constants have been reported for all states. Our data show excellent agreement with the experimental measurements. Time dependent density functional theory calculations using the LDA, BLYP, B3LYP, and SAOP functionals have been carried out for AgAu and the accuracy of TD-DFT has been compared with ab initio results.