How to find an appropriate journal to submit to when working in a new, unfamiliar field? I have developed a new method to form a single-atom chain (break junction) in physics, which so far has results from calculation and simulation but not yet experiment. 

How can I find out which journal is suitable for publishing the work?

My advisor is not familiar with my research field. I am exploring a whole new field.
Having had experience with this type of problem myself, I agree with the suggestions that you have been given in comments: the best way to figure out where to publish is to look at where the papers that you are citing in your related work are being published.

There is an additional challenge as well, however, which is that as a newcomer to the field, you are likely to have a more difficult time getting published because 1) you have not yet established credibility in this area, and so people will justifiably view your work with more skepticism, and 2) you are likely to be insufficiently aware of key concerns and points of debate within the community, which can get you into unnecessary trouble with your reviewers.  

I would thus recommend a "publish early and often" strategy: rather than trying to send a major manuscript to a top publication venues immediately, start by sending a couple of more restricted manuscripts to less difficult but still respectable targets.  By doing this, you can gain experience with the community's expectations and start building your reputation as a good practitioner in the area, both of which will later help you to be able to publish in higher impact venues.