Closed bannanc closed 7 years ago
In the absence of any deep chemical insight on my part, I'm tempted to go with a length of about 1.38 and a force constant which is the average of the ones listed. :) But if you
This is one it would be interesting to revisit when we explore partial bond order -- I wonder if the force constant and length differences GAFF2 is attempting to capture here are something which is captured by the semiempirical calculation so we could just interpolate smoothly...
@davidlmobley I pretended like I remembered o-chem yesterday and tried to draw out some structures and think about what would make the H-P bond stronger. Naively I assume something in the p2 and p4 types makes it more likely to polarize the bond making it stronger, otherwise H and P have similar electronegativities. I also tried to make guesses about which of these phosphorous is more common. It seems like there are possibly two distinct groups here, I think it makes more sense to round one of them knowing that might be bad for some case and good for others, instead of being bad for everything.
[#1:1]-[#15:2] 200. 1.4
Sounds good to me, @bannanc . The idea of two distinct groups means this would also be a good case for follow up with QM in the not-too-distant future, which would be nice.
In pull request #43
Looking at GAFF2 for inspiration. It has a dedicated hydrogen type for hydrogen bound to phosphorous (hp).
Here are the H-P bonds:
Relevant phosphorous atom types
I'm having a hard time making a decision about the hydrogen-phosphorous bond, but it seems like it would be better to keep just 1 H-P bond for now.