Mathematica help with noncommutative operator manipulations
- To: mathgroup at smc.vnet.net
- Subject: [mg34205] Mathematica help with noncommutative operator manipulations
- From: "Mark Pilloff" <mdp1 at uclink4.berkeleyREMOVETHIS.edu>
- Date: Thu, 9 May 2002 05:16:15 -0400 (EDT)
- Organization: Texas A&M University, College Station, Texas
- Sender: owner-wri-mathgroup at wolfram.com
Hi, I'm a novice Mathematica user and I'm working with a rather complicated expression involving quantum mechanical operators. The basic form is a sum of terms, each of which is a product of from 2 to 5 noncommuting operators. However, I want to expand each operator A into the form A = c + B where B is another noncommuting operator but c is an ordinary number (a multiple of the identity if you prefer). The resulting expressions will have a lot of terms, a few of which will combine after taking advantage of the commuting nature of the c-numbers. I'm looking for advice on how to set this up in Mathematica. I know that there's a noncommutative multiply operator ** built-in, but I couldn't get this to do anything useful (for example, it wouldn't expand (a+b)**(c+d) into 4 terms). Plus I have to deal with some terms which do commute with all others. Any help is greatly appreciated. Thanks, Mark