Physical properties of solids elucidated by zooming in and out of high resolution

In a recent paper published in EPJ E, Maziar Heidari, from the Max Planck Institute for Polymer Research, Mainz, Germany and colleagues make the accurate model in high-resolution coincide seamlessly with an exactly solvable representation at lower resolution.

The ideal, simpler model is a kind of naked representation of atoms or molecules, which do not interact among themselves. Previous studies have applied this strategy to liquids, but in this study,the authors apply it for the first time to a model solid coupled to an ideal crystal, in which atoms have restricted movements and do not interact, dubbed Einstein crystal. The team were able to compute its thermodynamic properties -- e.g. temperature and free energy -- at a reduced computational cost.

In this type of simulation, called adaptive resolution simulations, the resolution of a molecule depends on its position in space. In the transition region between the two resolutions, molecules adapt to one model or the other. This is an efficient way of computing the relevant thermodynamic characteristics of the actual solid by decomposing them in an ideal contribution -- from the simplified model -- and another term, specific to the particular system. The methodology combines the simplicity of ideal models with the chemical accuracy of realistic representations.