$ sudo apt-get update
$ sudo apt-get install libxmpi4 

libxmpi4 is installed in your system.

Make ensure the libxmpi4 package were installed using the commands given below,

$ sudo dpkg-query -l | grep libxmpi4 *

You will get with libxmpi4 package name, version, architecture and description in a table

libxmpi4 package basic information: