Creating membership files from xyz files

Let's say you want to plot the density of states for a molecular complex, you must separate it into its components and create membership files for each part of the complex. You can now easily do that by just preparing the individual geometry (xmol) files for the different parts of the molecule, and then create the membership files from those.
What you need to do is the following; let's suppose that you want to plot the density of states for TCNE-Benzene, the XMOL.DAT file for it looks like:

22
TCNE-Benzene
6 0.00000 1.39879 -2.10066
6 0.00000 -1.39879 -2.10066
6 1.21315 0.69955 -2.10096
6 -1.21315 0.69955 -2.10096
6 1.21315 -0.69955 -2.10096
6 -1.21315 -0.69955 -2.10096
6 0.00000 0.68630 1.54254
6 0.00000 -0.68630 1.54254
6 -1.22090 1.43405 1.55351
6 1.22089 1.43405 1.55351
6 -1.22090 -1.43405 1.55351
6 1.22089 -1.43405 1.55351
1 0.00000 2.49132 -2.10484
1 0.00000 -2.49132 -2.10484
1 2.15873 1.24667 -2.10250
1 -2.15873 1.24667 -2.10250
1 -2.15873 -1.24667 -2.10250
1 2.15873 -1.24667 -2.10250
7 -2.20482 2.05448 1.57450
7 2.20482 2.05448 1.57450
7 -2.20482 -2.05448 1.57450
7 2.20482 -2.05448 1.57450

You can open this file with Jmol and by use of the right-click menu get it to display only the TCNE by selecting all the atoms and then unselect the Benzene. If you choose now the option "Display selected only" it will hide the Benzene and display only the TCNE. You can now write it to a file with the command write xyz "TCNE.xyz" which will create an xyz file with only the TCNE:

10
TCNE
C 0.00000 0.68630 1.54254
C 0.00000 -0.68630 1.54254
C -1.22090 1.43405 1.55351
C 1.22089 1.43405 1.55351
C -1.22090 -1.43405 1.55351
C 1.22089 -1.43405 1.55351
N -2.20482 2.05448 1.57450
N 2.20482 2.05448 1.57450
N -2.20482 -2.05448 1.57450
N 2.20482 -2.05448 1.57450

You can do the same to create an xyz file for the Benzene:

12
Benzene
C 0.00000 1.39879 -2.10066
C 0.00000 -1.39879 -2.10066
C 1.21315 0.69955 -2.10096
C -1.21315 0.69955 -2.10096
C 1.21315 -0.69955 -2.10096
C -1.21315 -0.69955 -2.10096
H 0.00000 2.49132 -2.10484
H 0.00000 -2.49132 -2.10484
H 2.15873 1.24667 -2.10250
H -2.15873 1.24667 -2.10250
H -2.15873 -1.24667 -2.10250
H 2.15873 -1.24667 -2.10250

After you have both files created you can now run the python script attached to this article that will create a membership file from the geometry file that you just created, there is a catch though; right now it only takes atom numbers and not letters, so you must convert your geometry files from atom letters to numbers.
If you open the python script you will find the following lines that you have to modify to adjust to your needs:

# Total geometry file name
filein1='XMOL.DAT'
# Membership geometry file name
filein2='c60.xyz'
# Membership file name
fileout='mem1.mem'

where XMOL.DAT is file that contains the full geometry of the complex. c60.xyz is the name of the geometry file for the part of the complex youy want to process, and mem1.mem is the name of the membership file that will be created.
Once you have this files, you can now create your density of states data files from the membership files that were created by this process.