Computation of the temperature dependence of the heat capacity of complex molecular systems using random color noise.

We propose a method for computing the temperature dependence of the heat capacity in complex molecular systems. The proposed scheme is based on the use of the Langevin equation with low-frequency color noise. We obtain the temperature dependence of the correlation time of random noises, which enables us to model the partial thermalization of high-frequency vibrations. This purely quantum effect is responsible for the decreasing behavior of the specific heat c(T) in the low-temperature regime. By applying the method to carbon nanotubes and polyethylene molecules, we show that the consideration of the color noise in the Langevin equation allows us to reproduce the temperature evolution of the specific heat with a good accuracy.