  In order to study electron-transfer mediated chemical processes on a metal
surface, one requires not one but two potential energy surfaces (one ground
state and one excited state) as in Marcus theory. In this letter, we report
that a novel, dynamically-weighted, state-averaged constrained CASSCF(2,2)
(DW-SA-cCASSCF(2,2)) can produce such surfaces for the Anderson Impurity model.
Both ground and excited state potentials are smooth, they incorporate states
with a charge transfer character, and the accuracy of the ground state surface
can be verified for some model problems by renormalization group theory. Future
development of gradients and nonadiabatic derivative couplings should allow for
the study of non-adiabatic dynamics for molecules near metal surfaces.
