Professor Ning Xu from Department of Physics at University of Science and Technology of China has achieved some important progress on the statistical study of the potential energy landscape (PEL), in collaboration with Professor Daan Frenkel from Department of Chemistry at University of Cambridge and Professor Andrea Liu from Department of Physics and Astronomy at University of Pennsylvania. The work has been published in Physical Review Letters on June 17, 2011 (Phys. Rev. Lett. 106, 245502 (2011)).
In many body systems, if the potential energy is plotted as a function of particle coordinates, the PEL is constructed, as a complicated multi-dimensional surface. The PEL consists of an astronomically large number of basins of attraction whose bottoms are local potential energy minima, i.e. meta-stable configurations accessible at zero temperature. In excitations, the system walks randomly in the PEL. The PEL is very important in the understanding of many physical phenomena such as crystallization, melting, glass transition, jamming transition, plasticity, and protein folding.
Professor Ning Xu and his collaborators developed a novel method based on the free-energy calculation to directly measure the size of a single basin of attraction in the PEL, which makes it possible to statistically measure the number of distinct basins of attraction and the configurational entropy from sampling. Unlike all the previous methods which were based on specific assumptions, this new method does not rely on any assumptions, which is in itself a very important and useful result in the development of theories. Moreover, the ideas applied in this work are stimulating to some related studies.
This work was partly supported by the National Natural Science Foundation of China No. 11074228.