arXiv subjects

Le-Cheng Gong

Publications and source records attributed to Le-Cheng Gong.

3 recordsLinked to original sources

arXiv2019

Solution to the key problem of statistical physics -- calculations of partition function of many-body systems

The key problem of statistical physics standing over one hundred years is how to exactly calculate the partition function (or free energy) of many-body interaction systems, which severely hinders application of the theory for realistic systems. Here we present a novel approach that works at least four orders faster than state-of-the-art algorithms to the problem and can be applied to predict thermal properties of large molecules or macroscopic condensed matters via \emph{ab initio} calculations.The method was demonstrated by C$_{60}$ molecules, solid and liquid copper (up to $\sim 600$GPa), solid argon, graphene and silicene on substrate, and the derived internal energy or pressure is in a good agreement with the results of vast molecular dynamics simulations in a temperature range up to $2500$K, achieving a precision at least one order higher than previous methods. And, for the first time, the realistic isochoric equation of state for solid argon was reproduced directly from the partition function.

cond-mat.stat-mech↗

arXiv2019

Comparison of two efficient methods for calculating partition functions

In the long-time pursuit of the solution to calculate the partition function (or free energy) of condensed matter, Monte-Carlo-based nested sampling should be the state-of-the-art method, and very recently, we established a direct integral approach that works at least four orders faster. In present work, the above two methods were applied to solid argon at temperatures up to $300$K, and the derived internal energy and pressure were compared with the molecular dynamics simulation as well as experimental measurements, showing that the calculation precision of our approach is about 10 times higher than that of the nested sampling method.

cond-mat.stat-mech↗

arXiv2019

Calculating the free energy of 2D materials on substrates

A method was developed to calculate the free energy of 2D materials on substrates and was demonstrated by the system of graphene and γ-graphyne on copper substrate. The method works at least 3 orders faster than state-of-the-art algorithms, and the accuracy was tested by molecular dynamics simulations, showing that the precision for calculations of the internal energy achieves up to 0.03% in a temperature range from 100 to 1300K. As expected, the calculated the free energy of a graphene sheet on Cu (111) or Ni (111) surface in a temperature range up to 3000K is always smaller than the one of a γ-graphyne sheet with the same number of C atoms, which is consistent with the fact that growth of graphene on the substrates is much easier than γ-graphyne.

cond-mat.mtrl-sci↗