1***,h2o !A title 2r=1.85,theta=104 !set geometry parameters 3geometry={nosym, 4 O; !z-matrix geometry input 5 H1,O,r; 6 H2,O,r,H1,theta} 7hf !closed-shell scf 8MP2 !second-order Moeller-Plesset perturbation theory 9