Regarding error when i used fix efield command

Dear All,
I am getting an error (Unknown fix style (…/modify.cpp:782)), when i am using fix efield command
in the script given below. How i run script with fix efield command.
Thanks in advance.

Parameters and constants

variable a equal 0.418e-3
variable q equal -11940*1.6e-19

Dear All,
I am getting an error (Unknown fix style (../modify.cpp:782)), when i am
using fix efield command
in the script given below. How i run script with fix efield command.

by using a LAMMPS executable, that contains the command. a lot of
LAMMPS' features are part of packages and thus only available when
that package is installed during compilation. fix efield is part of
the MISC package, for example.

you can check whether a command is available in your executable by
running it with the -h flag.

axel.