Vapor pressures and heats of sublimation of crystalline β-cellobiose from classical molecular dynamics simulations with quantum mechanical corrections.
In this paper, we report the calculation of the enthalpy of sublimation, Δ(sub)H, as a function of temperature of crystalline β-cellobiose from molecular dynamics (MD) simulations, using two popular carbohydrate force fields. Together with the entropy difference between the solid and the vapor, ΔS, evaluated at atmospheric pressure, Δ(sub)H gives the vapor pressure of cellobiose over the solid phase as a function of T. It is found that when quantum mechanical corrections to the enthalpy calculated from the distribution of normal modes is applied both force fields give Δ(sub)H close to experiments. The entropy change, ΔS, which is calculated within a harmonic approximation becomes too small, leading to vapor pressures that are too low. These findings are relevant to MD simulations of crystalline carbohydrates in general, e.g., native cellulose.
Wallenberg Wood Science Center, KTH Royal Institute of Technology , SE-10044 Stockholm, Sweden.
Jakob
J
Wohlert
D002475:Cellobiose / Q000737:chemistry*; D019277:Entropy; D008962:Models, Theoretical; D056004:Molecular Dynamics Simulation; D044367:Phase Transition; D011789:Quantum Theory; D013696:Temperature; D055548:Vapor Pressure
D002475:Cellobiose