Comparing simulated specific heat of liquid polymers and oligomers to experiments
Hongyu Gao, Thalia J. L. Menzel, Martin H. Müser, Debashish Mukherji
Abstract
The field of atomistic simulations of polymers is in a mature stage, yet accurate predictions of their specific heat are very rare. The main difficulty stems from the quantum-mechanical nature of intramolecular vibrations. They call for either full, tedious quantum-mechanical treatments, or, for proper corrections of classical simulations. Here, the authors adopt an existing method, which defines a specific heat for a harmonic reference, to estimate the specific heat difference between classical and quantum-mechanical systems and use this as a correction factor. Thereby, they predominantly correct the stiff, high-frequency harmonic modes, while leaving the specific-heat contributions of the slow (anharmonic) modes intact. The results compare well to experimental data.