Prerequisites
=============
- Python 2.6.5 or later (3.x untested)
- Minuit2 (http://seal.web.cern.ch/seal/snapshot/work-packages/mathlibs/minuit/)
- pyminuit (http://code.google.com/p/pyminuit/)
- CRYSTAL code (http://www.crystalsolutions.eu/)
  note: you can adjust the script to work with other quantum chemistry 
        program packages as well by deriving a new optimizer 
        from base class BSOptimizer

Usage
=====
- Adjust variables at the top of Pcrystal09_bsopt.py:
  crystalExe, crystalVersion, mpi, copyCmd, grepCmd. 
- You need a crystal input that optimally only comes with modest 
  computational demands.
  In order to turn this input into a template file, designate variables 
  to be optimized with the notation ${...} (see e.g. scf3_bsopt.template). 
  Exponents should start with the letter 'a' (this is important 
  for constraints to work properly), coefficients with the letter 'd', 
  the remaining letters and numbers are arbitrary. 
- You will need to supply a fort.20 file from a previous single point calculation. 
  (Use the '-i' command line option for Pcrystal09_bsopt.py 
  to remove the variable tags from the template.)
- Run Pcrystal_bsopt.py by specifying the template file (-t option) and 
  the guess (-g option). 

Hints
=====
- Use simple systems that ideally can be calculated using conventional SCF settings 
  (i.e. omit SCFDIR keyword). 
- Use as few k points as possible. 
- Try to optimize a subset of variables first, e.g. start with contraction 
  coefficients only.