$ sudo apt-get update
$ sudo apt-get install debichem-molmech 

debichem-molmech is installed in your system.

Make ensure the debichem-molmech package were installed using the commands given below,

$ sudo dpkg-query -l | grep debichem-molmech *

You will get with debichem-molmech package name, version, architecture and description in a table

debichem-molmech package basic information: