usage for OPUS_CA:

1. calculate energy for single protein chain:

just run "./ca_energy";
in the next line,input pdb filename and return;
energy value will show up in the next line.

Afterwards, it's ready for the next calculation.

2. calculate energy for multiple protein chains:

run "./ca_energy < inputfile";
here inputfile is a text file with one pdb filename in each line.
energy values for all protein chains will be calcualted respectively and show up in new lines.

NOTE: 
1. only C-alpha atoms are required and read. In current version, pdb files should contain only single chain.
2. all energy data files should be in "energydata" directory along with the excutable.
3. the environment for the executable is X86, LINUX , both 32bit and 64bit should be ok.
4. use Ctrl-C to quit program
 
