Energetics and partition function of H₃+ molecular ion

الأصل · EN

Full NVT quantum statistics of the H₃+ ion is simulated at low densities using the path integral Monte Carlo approach. For the first time, the molecular total energy, partition function, free energy, entropy and heat capacity are evaluated in temperatures relevant for planetary atmospheric physics. Temperature and density dependent dissociation recombination reaction balance of the molecule and its fragments above 4000 K is described, and also, the density dependence of thermal ionization above 10 000 K is demonstrated. We introduce a new well-behaving analytical model for the molecular partition function of the H₃+ ion for the temperature range below dissociation and fit the parameters to the energetics from our simulations. The approach presented here can be regarded as an extension of the traditional ab initio quantum chemistry beyond the Born--Oppenheimer approximation to description of nonadiabatic phenomena, and even further, account of nuclear quantum dynamics.