spelling correction: vanDelWaalsRadius TO vanDerWaalsRadius

[unojoe2]

I looked up spelling for this item and found no reference to the spelling used.
I know it may cause some of the code in other parts of the package to have errors if just the JSON file is updated, so please be sure to fix all and push.
If I have time to repair these connections, I will post the updated code.
(my lack of experience showing here...)
If necessary, push update to branches and/or pull requests, and/or add version numbers...
Thanks for sharing the data!!
I'll probably be building on it, comparing it, and posting an appended dataset if all goes well.