Hello gromacs user: i´m trying to obtain the membrane density of a dppc-dppe membrane, but i don´t know very well the command that i need to use. I have an idea: gmx_density -f file.xtc -n file.ndx -s file.tpr -ei file.dat -o file.xvg. File.dat corresponds to electrons.dat of dppc and/or dppe. Is this correct?