DynHeMat: A program for zero-point averaged dynamics of pure and doped helium nanodroplets

DynHeMat is a parallel program aimed at modeling the dynamics of pure and doped helium nanodroplets (HNDs) by means of zero-point averaged dynamics (ZPAD), a method where the quantum nature of helium atoms is taken into account through the use of a He-He pseudopotential which includes zero-point effects of helium clusters on an average manner. Three He-He pseudopotentials, defined for applications in different contexts, are implemented. Large HNDs can be formed by successive coalescences of smaller HNDs keeping in mind that, depending on the HND size and He-He pseudopotential in use, the liquid character of the HND is more or less pronounced. Files containing the positions and velocities of HNDs formed with the three aforementioned He-He pseudopotentials are collected in a local databank, called ZPAD_DB. ZPAD simulations can be carried out at constant energy or temperature, then enabling the user to investigate collision, coagulation or submersion processes in pure or doped HNDs. Impurities can be rare-gas atoms (Ne, Ar, Kr, Xe and Rn), alkali atoms (Li, Na, K, Rb, Cs), or homogeneous clusters composed of such atoms. The program provides information on trajectories, namely positions, velocities, energies, radial distribution functions, and the initial distribution of HND surface atoms. Extension to other impurities or He-He pseudopotentials is made possible by the current structure of the program and keyword system.