It turns out the reason that we had to turn gradient clipping off to make H4 work was not because gradient clipping is bad, but because I broke the gradient clipping a month or so ago when I refactored the energy gradient code.
Fix is simple - just need to use local_energies instead of local_energies_noclip in line 231 of physics/core.py. Now things work as expected again.
It turns out the reason that we had to turn gradient clipping off to make H4 work was not because gradient clipping is bad, but because I broke the gradient clipping a month or so ago when I refactored the energy gradient code.
Fix is simple - just need to use local_energies instead of local_energies_noclip in line 231 of physics/core.py. Now things work as expected again.
PTAL @tkayq @nilin