On the contribution of intramolecular zero point energy to the equation of state of solid H2

Experimental evidence shows that the internal zero-point energy of the H2 molecule exhibits a relatively strong pressure dependence in the solid as well as changing considerably upon condensation. It is shown that these effects contribute about 6% to the total sublimation energy and to the pressure in the solid state. Methods to modify the ab initio isolated pair potential to account for these environmental effects are discussed.