Cyclobutane - puckering

Owned by Pavan Behara

Last updated: Jun 24, 2021

2 min read

Parameters applied to this are:

C4H8 ['a2', 'a7', 'a9', 'b1', 'b83', 'n16', 'n2', 't2', 't3', 't4']

	System	Bonds	Angles	Dihedrals	Impropers
FF		RMSD	RMSD	RMSD	RMSD
1.0.0	1_19370395_C4H8	0.019	2.663	23.27	0
1.2.0	1_19370395_C4H8	0.019	2.674	23.247	0
1.3.0	1_19370395_C4H8	0.019	2.701	23.249	0
2.0.0 rc1	1_19370395_C4H8	0.018	2.604	23.243	0
2.0.0 refit w/ dd	1_19370395_C4H8	0.017	2.254	16.588	0

QM in green, dark orange is with Sage refit with inclusion of dihedral rmsd in optgeo target objective function.

Rest all below are from

1.0.0 - yellow, 1.2.0 - magenta

1.3.0 - cyan, 2.0.0 rc1 - wheat tint

Change in parameters with the inclusion of dihedral rmsd

diff between 2.0.0 rc and reift w/ dd	Δ(pararmeter)	Δ(pararmeter)		smarts
parameter	angle in degrees	k in kcal/(molrad*2)
a2	0.34	0.71		"[#1:1]-[#6X4:2]-[#1:3]"
a7	2.3	12.35		"[#6r4:1]-;@[#6r4:2]-;@[#6r4:3]"
a9	0.82	17.51		"[!#1:1]-[#6r4:2]-;!@[#1:3]"
	length in ang.	k in kcal/(ang*2mol)
b1	0.00	2.18		"[#6X4:1]-[#6X4:2]"
b83	0.00	0.15		"[#6X4:1]-[#1:2]"
	k1 in kcal/mol	k2 in kcal/mol	k3 in kcal/mol
t2	-0.05	0.03	0.02	"[#6X4:1]-[#6X4:2]-[#6X4:3]-[#6X4:4]"
t3	-0.01			"[#1:1]-[#6X4:2]-[#6X4:3]-[#1:4]"
t4	-0.03			"[#1:1]-[#6X4:2]-[#6X4:3]-[#6X4:4]"

% change in parameter values

Parameter	Sage rc1	Sage refit w/ dd	% change
a2, angle	115.60	115.27	-0.29%
a2, k	97.55	98.26	0.73%
a7, angle	122.17	119.88	-1.88%
a7, k	77.00	64.65	-16.04%
a9, angle	119.14	119.96	0.69%
a9, k	90.36	107.87	19.38%

b1, length	1.52	1.52	0.12%
b1, k	529.24	527.06	-0.41%
b83, length	1.09	1.09	-0.17%
b83, k	740.09	740.25	0.02%

t2, k1	0.09	0.14	50.83%
t2, k2	0.32	0.28	-10.64%
t2, k3	0.32	0.31	-4.85%
t3, k1	0.19	0.20	7.09%
t4, k1	0.10	0.13	25.66%

*angle in degrees, angle k in kcal/(ang**2*mol), bond length in angstroms, bond k in kcal/(ang**2*mol), torsion k in kcal/mol