Test fits with linear- and cyclo- alkanes
PhAlkEthOH dataset doesn’t have hessians, so with just the opt geo targets of linear (1 to 7) and cyclo alkanes (3 to 9), separately and both combined optimized H-C-H angle (parameter a2), and the bonds C-C (parameter b1) and C-H (parameter b83) with 90 deg and 1 Ang. as starting values respectively.
Targets:
Here are the final parameter values:
Parameter | Initial values taken | Linear + cyclo alkanes | Cyclo alkanes only | Linear alkanes only | Std. dev. of the three | 1.3.0 for reference |
b1, length, [#6X4:1]-[#6X4:2] | 1.00 | 1.50 | 1.50 | 1.46 | 0.02 | 1.52 |
b1, k, [#6X4:1]-[#6X4:2] | 500.00 | 488.76 | 487.34 | 488.01 | 0.58 | 517.22 |
b83, length, [#6X4:1]-[#1:2] | 1.00 | 1.09 | 1.09 | 1.09 | 0.00 | 1.09 |
b83, k, [#6X4:1]-[#1:2] | 700.00 | 699.88 | 699.88 | 699.86 | 0.01 | 754.07 |
a2, angle, [#1:1]-[#6X4:2]-[#1:3] | 90.00 | 110.51 | 110.46 | 110.09 | 0.19 | 114.29 |
a2, k, [#1:1]-[#6X4:2]-[#1:3] | 60.00 | 89.77 | 90.36 | 82.16 | 3.74 | 66.55 |
*length in angstroms, angle in degrees, k in kcal/mol/ang^2 or kcal/mol/rad^2
Assigned parameters for each, picked only a2, b1, b83 for fits:
CH4 ['a2', 'b83', 'n16', 'n2'] C2H6 ['a1', 'a2', 'b1', 'b83', 'n16', 'n2', 't3'] C3H8 ['a1', 'a2', 'b1', 'b83', 'n16', 'n2', 't3', 't4'] C4H10 ['a1', 'a2', 'b1', 'b83', 'n16', 'n2', 't2', 't3', 't4'] C5H12 ['a1', 'a2', 'b1', 'b83', 'n16', 'n2', 't2', 't3', 't4'] C6H14 ['a1', 'a2', 'b1', 'b83', 'n16', 'n2', 't2', 't3', 't4'] C7H16 ['a1', 'a2', 'b1', 'b83', 'n16', 'n2', 't2', 't3', 't4'] C3H6 ['a3', 'a4', 'a6', 'b1', 'b83', 'n16', 'n2', 't15', 't16'] C4H8 ['a2', 'a7', 'a9', 'b1', 'b83', 'n16', 'n2', 't2', 't3', 't4'] C5H10 ['a1', 'a2', 'b1', 'b83', 'n16', 'n2', 't2', 't3', 't4'] C6H12 ['a1', 'a2', 'b1', 'b83', 'n16', 'n2', 't2', 't3', 't4'] C7H14 ['a1', 'a2', 'b1', 'b83', 'n16', 'n2', 't2', 't3', 't4'] C8H16 ['a1', 'a2', 'b1', 'b83', 'n16', 'n2', 't2', 't3', 't4'] C9H18 ['a1', 'a2', 'b1', 'b83', 'n16', 'n2', 't2', 't3', 't4']
Test fits with sulfonamide (optimizing only a30, a31)
Targets
Torsion drives, opt geo, and vib freq targets that match to a30, a31 from release-1.2.0 targets
Replacing a30 and a31 in openff_unconstrained-1.3.0 with Frostt99 parameters (as starting point) and running the following fits
refit using all the targets (td + opt + vib freq)
refit with only opt_geo targets
refit with only vib_freq targets
refit with only td targets
refit with td+opt_geo targets
test fit with a child parameter for a30
a30b *=[#16X4]=*initial value for angle parameter as 125 degrees, and k same as a30 (140)
Fits in progress, most of them crossed five iterations and obj. function values are converging, parameter values at the last iteration as of now (will update after the runs complete)
Initial values | td+opt+vib | opt | vib freq | td | td+opt | td+opt+vib + child | |
Frostt99 | 1 | 2 | 3 | 4 | 5 | 6 | |
a30, angle | 109.5 | 113.3 | 109.9 | 114.6 | 109.6 | 113.1 | 112.5 |
a30, k | 140.0 | 147.1 | 162.7 | 165.2 | 95.9 | 139.7 | 173.2 |
a31, angle | 109.5 | 107.7 | 102.0 | 113.9 | 110.8 | 107.5 | 109.9 |
a31, k | 120.0 | 122.8 | 150.9 | 205.0 | 35.3 | 117.7 | 117.5 |
a30b, angle | 125.0 | 123.1 | |||||
a30b, k | 140.0 | 177.2 |
*angle in degrees, k in kcal/mol/rad^2