Ab initio study of the HCOOHAr van der Waals complex

The structure, energetics and vibrational properties of the van der Waals complex between HCOOH and Ar have been studied by ab initio molecular orbital theory. Three local minima, two in the plane of HCOOH and one non-planar, could be found with interaction energies ranging between −1.3 and −1.9 kJ mol−1. The vibrational properties of HCOOH were found to be unperturbed except in the case of the interaction from the OH-tail. The shift in the OH absorption should enable the identification of this complex structure easily from the IR spectrum.