side-chain torsion corrections parameterized to match the quantum chemical rotational surface.
* - An AMBER-based forcefield and webtool for modeling common non-natural amino acids in proteins in condensed-phase simulations using the ff03 charge model. The charges have been reported to be correlated with hydration free energies of corresponding side-chain analogs.

AMBER has integrated modified amino acid changes into phosaa14SB/phosaa19SB and ff14SB_modAA. Parameters from ff15ipq are useful for unnatural modifications. Official guidance