  Many-body perturbation theory within the G$_0$W$_0$ approximation is used to
determine molecular orbital level alignment at a liquid water/Pt(111) interface
generated through $ab~ initio$ molecular dynamics. Molecular orbital energy
levels are shown to depend both on the position of H$_2$O molecules within the
liquid relative to the surface and the details of their local bonding
environment. Standard density functional theory calculations disagree
qualitatively with level alignment predicted by many-body perturbation theory.
