Table 3 SMIRKS patterns used for LJ typing, with well-depth ε (kcal/mol) and effective radius r1/2 (Å) parameter values used to initiate parameter optimization. The first row for each element (bold) gives the parameters used when that element had only a single type. In this case, the SMIRKS pattern was replaced with a SMIRKS string recognizing all atoms of this element. Starting parameters for the polar/apolar hydrogen models are given in the bottom rows. The last column gives the SMIRNOFF LJ type definitions from which these initial values were drawn.
From: Data-driven analysis of the number of Lennard–Jones types needed in a force field
SMIRKS | Description | Initial ε | Initial r1/2 | SMIRNOFF SOURCE |
|---|---|---|---|---|
Hydrogen | ||||
[#1:1]-[#6X4] | Hydrogen bound to a sp3 Carbon | 0.0157 | 1.4870 | [#1:1]-[#6X4] |
[#1:1]-[#6X3] | Hydrogen bound to a sp2 Carbon | 0.0150 | 1.4590 | [#1:1]-[#6X3] |
[#1:1]-[#7] | Hydrogen bound to an Oxygen | 0.0157 | 0.6000 | [#1:1]-[#7] |
[#1:1]-[#8] | Hydrogen bound to a Nitrogen | 5.27E-05 | 0.3000 | [#1:1]-[#8] |
Carbon | ||||
[#6X3:1] | sp2 Carbon | 0.0860 | 1.9080 | [#6:1] |
[#6X4:1] | sp3 Carbon | 0.1094 | 1.9080 | [#6X4:1] |
[#6X2:1] | sp Carbon | 0.2100 | 1.9080 | [#6X2:1] |
Oxygen | ||||
[#8X1:1] | Carbonyl Oxygen | 0.2100 | 1.6612 | [#8:1] |
[#8X2H0 + 0:1] | Alcohol Oxygen | 0.1700 | 1.6837 | [#8X2H0 + 0:1] |
[#8X2H1 + 0:1] | Ether Oxygen | 0.2104 | 1.7210 | [#8X2H1 + 0:1] |
Nitrogen | ||||
[#7X1:1] | Nitro Nitrogen | 0.1700 | 1.8240 | [#7:1] |
[#7X3:1] | Amine Nitrogen | 0.1700 | 1.8240 | [#7:1] |
Polar and Apolar Hydrogens | ||||
[#1:1] -[#6] | Apolar Hydrogen | 0.0157 | 1.4870 | [#1:1]-[#6X4] |
[#1:1]-[#7,#8] | Polar Hydrogen | 0.0157 | 0.6000 | [#1:1]-[#7] |
