Fix file existence check in ChargemolAnalysis to verify directory instead.

[lllangWV]

atomic_densities dir for chargemol is a dir not a file.

I am working with chargemol in a high throughput context with Atomate2. When trying to perform chargemol calculations I could not get past if not os.path.isfile(atomic_densities_path):. I believe this is because if you provide a directory, which is what atomic_densities_path should be, this will always trigger preventing the operation. Unless I am wrong with the functioning of os.path.isfile.

Summary

Major changes:

• feature 1: Changed isfile to isdir
• fix 1: Changed isfile to isdir

[mkhorton]

Thanks for flagging this @lllangWV

Tagging @mhsiron @Andrew-S-Rosen for this one, I haven't used the Chargemol functionality myself. Not clear how this worked previously if it is an error?

[Andrew-S-Rosen]

Almost certainly this is the correct patch, although I must admit that I don't think I've used this function in a long time (likely before any refactoring).

[DanielYang59]

Not clear how this worked previously if it is an error?

I guess this is an oversight from (very likely done by batch regular expression replacement or similar, as this part is not covered by unit test):

• os.path.(exists->isfile) #3690

[shyuep]

Thanks.