I use this command:
sh moltemplate.sh oplsaa.ltBut I get this error:
Error: There are no atoms in your system.
That is because the "oplsaa.lt" file does not contain any "write("Data
Atoms")" sections or "new" commands.
In most of the moltemplate examples, moltemplate.sh is invoked this way:
moltemplate.sh system.lt
(If you have vmd installed, I recommend using moltemplate.sh -vmd system.lt)
By convention, the file named "system.lt" usually describes the entire
system. It typically specifies the number of molecules, of each type,
you want in your system. It contains "import" statements which link
to the other .lt files. (In contrast, the other .lt files only
contain definitions of the various building-blocks you need, including
molecule types, and force-fields.)
In the "alkane_chain_single" example, the "system.lt" file contains this line:
polymer = new Alkane50
command which creates a copy of (instance of) the "Alkane50" molecule,
defined in "alkane50.lt". ("alkane50.lt" links to "ch2group.lt" and
"ch3group.lt" containing definitions of the CH2 and CH3 monomers use
to build the alkane polymer. All three of those files refer to
"oplsaa.lt", which contains only the OPLSAA force-field information.)