How to appropriately emphasize the importance of consulting more to a student? I'm a PhD student and a full-time researcher in my uni. This year I was assigned with supervising of one Bachelor's thesis. My PhD supervisor invented a topic, which is really interesting, but a really difficult one for this level (combination of quantum chemistry and neural networks).

Student, who assigned for that, has a programming background, so he doesn't have much experience in mathematics or a theoretical computer science. Nevertheless, I believed he can catch up and I had some literature prepared for him.

At first he didn't contact me for the first several weeks, which made me pretty nervous and I wrote him a polite reminding e-mail with a consultation suggestion. He came and we agreed on some plan. Several weeks later, on our second consultation he showed just a little real progress, but I still considered it ok, believing, that he's studying the underlying theory beforehand.

The problem is now, that he didn't show up since and I had to contact him again, only to find out, that he was too occupied by his job and that he will be writing e-mails with his progress.

So, I'm afraid, based on his behaviour, that he tries to appear independent and to develop the software for the thesis on his own. That could be a real problem as he will progress too slow without any guidance (he has NO previous experience with his topic, except programming skills).

So, my question is - how can I politely persuade him to communicate with me more often? I really want him to successfully finish his thesis, both because of my "score" during PhD and because I would otherwise feel guilty of ruining someone else's career.
I have a completely different background, I'm in the lab very often and so are my students. Still they can become quite independent and it can be hard to keep an eye on what they're doing exactly. 

Suggesting to communicate more and persuading them to ask more questions is (in my opinion) the wrong way to approach your problem. You cannot expect a bachelor level student to learn - all by himself - both running a project and the science that goes with the project. Maybe that could work for the top 1% of students.

I'd start having weekly meetings, and then it's your job to ask them questions, teach them stuff and keep them on track. Suggesting someone to ask questions doesn't really work, so you should really ask questions yourself that force them to communicate about the project. 

Really sitting down and discussing the project will lower the barriers on both sides. Your suggestions won't sound like orders, and there will be no e-mail record of their silly questions. Start slow before you start having any real expectations. 

At the moment I'd be surprised if they even started with the project.