Quantum power functional theory for many-body dynamics

We construct a one-body variational theory for the time evolution of nonrelativistic quantum many-body systems. The position-and time-dependent one-body density, particle current, and time derivative of the current act as three variational fields. The generating (power rate) functional is minimized by the true current time derivative. The corresponding Euler-Lagrange equation, together with the continuity equation for the density, forms a closed set of one-body equations of motion. Space-and time-nonlocal one-body forces are generated by the superadiabatic contribution to the functional. The theory applies to many-electron systems. (C) 2015 AIP Publishing LLC.