O-H flipping vibrations of the Cage water hexamer: An ab initio study

摘要: In the Cage[1] isomer of water hexamer, free O–H bonds two end-cap molecules can flip between “up” (u) and “down” (d) orientations, giving four conformers denoted uu, ud, du, dd. Using Moller–Plesset second order perturbation method large basis sets, we calculate fully relaxed potential energy curves as a function both u↔d torsional angles, φ1, φ2. These predict du lowest conformer, with uu nearly degenerate ud dd at 30–40 50–70 cm−1 higher energy, respectively. Along φ1 barriers are about 200 cm−1, along φ2 80 110 cm−1. The zero-point energies high, vibrational ground states strongly delocalized averaging cluster properties is important dipole moment components vary φ2: μa changes from +0.8 to +2.2 D, μb +0.5 +1.2 D, μc +1.4 −0.9 D. fundamental (H2O)6 predicted in range 65–72 cm−1 ...