Structural control of Ar–HF complexes using dc electric fields: a diffusion quantum Monte Carlo study

Using diffusion quantum Monte Carlo techniques, we study the structural changes induced in Ar–HF van der Waals complexes by strong (2.5–20 MV/m) dc electric fields. The external field couples the space-fixed and body-fixed orientation of the HF bond, ultimately leading to an increase in the collinear character of the Ar–HF complex. These effects can be explained in terms of a two-dimensional effective potential surface for the argon atom arising from a Born–Oppenheimer-type separation of the rapid HF librational motion and the motion of the argon atom.