How do I specify I do not want to perform a specific type of research on my CV? A couple of years back I did some research at a company in a field (Computational chemistry) that I am no longer interested in pursuing (To be blunt: I discovered that I dislike computational chemistry, and lack a certain numerical intuition needed to interpret the results). As I have this and a number of computer science classes on my CV several jobs I have applied for have added computational chemistry to my duties, which leaves me in the unpleasant position of explaining that I'd rather not do that type of research. (See edit below for an explanation of the process) 

I'd rather not take that experience off my CV, as it explains why my undergraduate degree is taking so long (I was working for a semester instead of taking classes), and my supervisor did offer me a good reference letter, since I was a good worker, despite the fact I didn't get great results. Also, to be frank, I'm an undergrad and would like to list it to stand out from the crowd a bit: Relevant work experience is much rarer then good marks. 

Is there a way I can include that position on my CV, but specify that I'd rather not peruse that field of research? Perhaps as a footnote or a comment intside that description of the job that 'This is a field of research I am no longer interested in perusing'?

EDIT: An explanation of how applying for summer jobs tends to work in my experience:
I'm an undergraduate chemistry major applying to be a research assistant over the summer. The general process for this is you find a professor doing the type of research you want, and email them your coverletter and CV. If they like you then they either hire you, or apply for a grant to get funding to hire you. Formal or informal interviews can take place at any time during this process, depending on how the professor likes to operate. Formal job descriptions are usually only placed on the grant after the student applies, it isn't listed on the profs website beforehand. Therefore I've applied to several synthetic chemistry groups then been either told I'll be expected to do some modelling as part of my job, or asked if I would be willing to do such research: The second option isn't so bad, but the first is rather awarded to explain, doubly so if I'm not told of this until after the grant is already awarded.
Usually, in an academic CV, you can distinguish between "Research Activities", which consist of all the research you've done in the past, and "Research Interest", which consist of all the research you want to do in the future. So, someone who would include a topic that you don't list in your research activities without asking you first would be a bit rude. 

However, in order to avoid this kind of cases, and not to be too explicit (that is, not saying "I don't to work on Computational Chemistry"), you can try, in your cover letter or your research interests to put a sentence like "Although I have a good background in Computational Chemistry, my research interests rather lie in ..." or "My background in Computational Chemistry taught me to [...], and I'm now interested in broadening/focusing my interest on [...]". That's a bit more subtle, but I guess the message should pass.