So you want to run Mathematica on a computer which is permanently connected to the physikcs department network. Installation and configuration differes, depending on who is managing this computer.

Mathematica is installed on all centrally managed Linux hosts by default. You run it by typing mathematica into a terminal window. You can start the non-graphical version by typing math. Older versions are also available by typing mathematica7 for example.

dreger@smart:~> math
Mathematica 8.0 for Linux x86 (64-bit)
Copyright 1988-2011 Wolfram Research, Inc.

In[1]:= 1+1

Out[1]= 2

To install Mathematica you simply select it from Control Panel → Programs and Features → Install a program from the Network:

You need to download the Mathematica installer from https://software.physik.fu-berlin.de. Install it on your computer and start the program.