Evaluation of the specific heat with quantum corrections

In classical Molecular Dynamics (MD), constant-volume specific heat is obtained from the change in energy with temperature, but it tends to be overestimated compared with experimental values. In this example, concepts from quantum statistical mechanics were introduced, applying quantum corrections to trajectories obtained from MD to evaluate specific heat more accurately. Applied to polystyrene (PS) and PMMA, the results at 300 K yielded values close to experimental data.

Use Cases Highlights

Evaluation of constant-volume specific heat with quantum corrections applied
Good agreement with experiments

Evaluation of constant-volume specific heat with quantum corrections applied

The density of states evaluated from Molecular Dynamics (MD) trajectories for PMMA is shown. The velocity autocorrelation function is Fourier-transformed to obtain the density of states, and quantum correction is applied using the Bose–Einstein distribution.

Density of states of PMMA evaluated by MD

Reference

[1] R. Bhowmika, S. Sihn, V. Varshney, A. K. Roy and J. P. Vernona, Polymer, 167, 176 (2019)
[2] C. Li, G. A. Medvedev, E. Lee, J. Kim, J. M. Caruthers and A. Strachan, Polymer, 53, 4222 (2012)
[3] Polymer Handbook 4th Edition, Wiley, New York (1999)

Details of analysis