I gave up after the third hypothesis and spending 11mins - sorry! My 4th hypothesis looked too similar to my second and I got rather confused. Too hard - unless I've missed a trick perhaps! I love your puzzles usually though so I'm sure it was a good one!
I started with a 20 x 20 depiction of the structure of a crystal. Multiple solutions of resulting hanjie, so I removed a column or a line and retested after each. Eventually got to this unique solution. Glad that the hanjie can be solved without knowing about crystal structure!
That was a helpful clue with the crystal structure. I went back to try again.....and managed it finally! It did make logical sense this time. Thank you for a fun challenge!