MC polybeads

Force Field: so far just masses, and nonbonded interactions (LJ,exp-6)

atom_prop structure removed and replaced by atom_rel[i_atom]
   (the relative index of a given i_atom is the only info needed
    in the builder).

mol_prop structure removed and replaced by mol_first_atm[i_mol]
   (the label of the first atom of a given i_mol is the only info 
    needed in the builder)

template_bonds structure removed and replaced by 3 arrays temp_bonds_1,
                                                          temp_bonds_2,
                                                          temp_bonds_ord
    (only temp_bonds_1 and temp_bonds_2 are used - in graphics only!)

combine strructure removed and replaced by an array combine[][][][]
   which contains only the overlap term (only thing used in the builder)

template_atoms structure removed and replaced by 9 arrays :
                                    temp_atm_pos[][][x,y,z]
				    temp_atm_mass[][]
				    temp_atm_lab[][]
				    temp_atm_type[][][]
				    temp_atm_nbr[][]
				    temp_atm_br[][][6]
				    temp_atm_ord[][][6]
				    temp_atm_sigma[][]
				    temp_atm_eps[][]

Modification from Prabal subroutines:

cells[NDIM] --> nc[NDIM]
n_p[NDIM]   --> nc_p[NDIM]

npotential_phantom.c --> potential_phantom.c

Additions inside the parameter file:
____________________________________

header_file_save, config_file_save : to save final config at the end of the
                                     run (ascii files)

phant_switch : if phant_switch = 1, use cell list with phantom
               if phant_switch = 0, use cell list without phantom (to be added)

neigh_switch : if neigh_switch = 0, N^2 search
               if neigh_switch = 1, cell list
               if neigh_switch = 2, neighbor list (using cell list)

kc : number of "subcells" (1 means cell of size r_off)
r_nl :  for neigh list

dr_max : max translational displacement of a molecule
ratio_dang_dr : ratio of the max angular displacement versus max translational
                displacement.
dh_max : max reshaping dimension of the box)

n_opt : number of MC sweeps before an optimization of the MC parameters
        (for now, just dr_max is optimized)

n_thermo : number of MC sweeps before writing instantaneous thermodynamics
           quantities to output file (binary)  

n_block : number of MC sweeps before a block average of the thermodynamics 
          quantities.

n_trajec : number of MC sweeps before writing trajectory file to output
           (binary).

##########################################################################
02/28/00

Here is the new version :

The code can now in principle handle mixture and different type of potential.
The interaction parameters are specified in two arrays :

comb_pot[i_type][j_type] which return an integer identifier for the type of
potential used for interaction between i_type and j_type atoms.

comb_par[i_type][j_type][MAX_PAR]  (where MAX_PAR = 20 ) which contains the parameters
of the interaction between atoms of type i_type and j_type.

We used a routine called convert_type to convert the string-type atom to integer_type 
atom, after reading input parameter file and header+config files.
