The structure of methane

Built into NRLMOL is the information to calculate the structure of methane. To create these files, run cluster in a directory without a CLUSTER or SYMBOL file. cluster will create an initial CLUSTER file that looks like this

GGA-PBE*GGA-PBE          (DF TYPE EXCHANGE*CORRELATION)
TD                       (TD, OH, IH, X, Y, XY, ... OR GRP)
2                        (NUMBER OF INEQUIV. ATOMS IN CH4)
0.00  0.00  0.00  6  ALL (R, Z, PSEUDOPOT. TYPE FOR CARBON)
1.20  1.20  1.20  1  ALL (R, Z, PSEUDOPOT. TYPE FOR HYDROGEN)
0.0 0.0                  (NET CHARGE AND NET SPIN)
 --------------OR-------------------
@XMOL.DAT
 IF YOU WISH TO START FROM AN XYZ XMOL FILE

There will also be a RUNS file and a PARSAV file.

Running cluster again will start an actual calculation. Depending on your system, you will have to run cluster between 3 and 7 times before convergence occurs. The final XMOL.DAT file should look like this

    5
Cluster output
    6    0.00000    0.00000    0.00000
    1    0.63276    0.63276    0.63276
    1    0.63276   -0.63276   -0.63276
    1   -0.63276    0.63276   -0.63276
    1   -0.63276   -0.63276    0.63276

The SYMBOL file will contain one entry for each time you had to run cluster.