Ab initio grand canonical Monte Carlo simulation of surfaces and nanoparticles.

E-mail: 
        Robert Wexler : rwexler@sas.upenn.edu
        Tian Qiu      : tianq@sas.upenn.edu

These python scripts simulate the structural evolution of surfaces or nanopartcles in the grand canonical ensemble. 
Quantum Espresso (QE) is launched to perform the structural relaxation and the total energy calculation.

Dependencies:
Python 2.6.9
MPI launcher (optional but strongly suggested)

Usage:
1. Prepare the QE pw executable file pw.x in the directory "bin"
2. Prepare the QE input file template in the directory "templates"
3. Prepare pseudopotential files for DFT calculations in the directroy "PSPs"
4. Prepare information of elements in "el_list.txt"
5. Set up the buffer length `buf_len` in "main.py"
6. Set up the chemical potential `mu_list` in "main.py"
7. Set up the QE launcher `call_qe` based on the MPI launcher in "main.py"
8. Run the command `python main.py structure.xsf el_list.txt`