Skip to main content
. Author manuscript; available in PMC: 2019 Nov 13.
Published in final edited form as: J Chem Theory Comput. 2018 Oct 30;14(11):6076–6092. doi: 10.1021/acs.jctc.8b00640

Figure 8. Example molecules with torsional errors in AMBER force fields uncovered in AlkEthOH.

Figure 8.

Shown are examples of molecules with torsions which were erroneously assigned generic torsional values in AMBER parm99, parm@Frosst, and GAFF/GAFF2 force fields, as uncovered by our testing of SMIRNOFF for AlkEthOH to ensure it could reproduce parm@Frosst energies. The errors found all involve torsions containing the H1, H2, or H3 parm@Frosst atom types (GAFF/GAFF2 types are equivalent but lowercase), used for hydrogens connected to carbons which are themselves connected to one, two, or three electron withdrawing groups (respectively). Carbons with attached hydrogens having the H1 atom type are highlighted in blue and carbons with hydrogens having the H2 atom type are highlighted in red; carbons here use the CT atom type and oxygens use OH if in hydroxyls and OS otherwise (GAFF/GAFF2 types c3, oh, and os respectively). Specifics of exactly how these errors originated and how they were addressed in our testing are explained in Section 2 of the Supporting Information.