This directory has a Makefile.lammps file with settings that allows LAMMPS to dynamically link to the VMD molfile library. This is required to use the USER-MOLFILE package and its interface to the dump and write_dump commands in a LAMMPS input script.

More information about the VMD molfile plugins can be found at http://www.ks.uiuc.edu/Research/vmd/plugins/molfile.

More specifically, to be able to dynamically load and execute the plugins from inside LAMMPS, you need to link with a system library containing functions like dlopen(), dlsym() and so on for dynamic linking of executable code into an executable. This library is defined by setting the molfile_SYSLIB variable in the Makefile.lammps file in this dir.

For Linux and most current unix-like operating systems, this can be kept at the default setting of "-ldl" (on some platforms this library is called "-ldld"). For compilation on Windows, a slightly different mechanism is used that is part of the Windows programming environment and this library is not needed.

See the header of Makefile.lammps for more info.