Short but sweet!
In order to generate high resolution images of the systems that I have been working with for Publications or my PhD thesis I recently discovered Tachyon rendering from VMD
Once you arrive that the scene that you like, in the vmd console type
render Tachyon filename.dat "/path/to/tachyon_binary" filename.dat -aasamples 12 -format TARGA -res 4096 4096 -o outfile.tga
The resolution is controlled by
-res X Y
VMD usually has a tachyon binary in its directory. In my case the path is: