Update lammps-tutorials.tex

Co-authored-by: Axel Kohlmeyer <akohlmey@gmail.com>

Author: simongravelle

lammps-tutorials.tex

@@ -2178,6 +2178,8 @@ \subsubsection{Stretching the PEG molecule}
 Running the \flecmd{pull-with-tip.lmp} file using LAMMPS will generate a trajectory file
 named \flecmd{pull.lammpstrj}, which can be opened in OVITO or VMD.
 
+Since the trajectory dump file does not contain information about topology and atom types, it is usually preferred to first write out a data file and import it directly (OVITO) or convert it to a PSF file (VMD) and load that before \emph{adding} the trajectory file to it.  When using \lammpsgui{} this process can be automated when using \guicmd{View in OVITO} or \guicmd{View in VMD} in the \guicmd{Run} menu. Then only the trajectory dump needs to be added.
+
 \subsection{Tutorial 4: Nanosheared electrolyte}
 \label{sheared-confined-label}