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Dear GLYCAM users,

I am trying to simulate interaction of polymers with sulphated cellulose, I observed that when I convert the .top and .crd file from amber to a LAMMPS data file, The sulphate group has the same bond type for both single bonded and double bonded oxygen atoms.

From the parameter file, the definition for the bond is as follows

S -O2  620.0    1.440       K calculated from methyl sulphate (eqm value from THEOCHEM 395/396 (1997) 107-122)

Residue info from PREP file.

SO3  INT 0
CORRECT OMIT DU BEG
-0.8370
1 DUMM DU  M  0 -1 -2  0.000   0.000    0.00     0.0000
2 DUMM DU  M  1  0 -1  0.500   0.000    0.00     0.0000
3 DUMM DU  M  2  1  0  1.296  74.264    0.00     0.0000
4 S1   S   M  3  2  1 10.884 119.491 -167.81     1.2450
5 O1   O2  E  4  3  2  1.446 106.410 -102.07    -0.6940
6 O2   O2  E  4  3  2  1.437 128.086  115.25    -0.6940
7 O3   O2  E  4  3  2  1.446  70.631    7.86    -0.6940

Shouldn’t these single and double bonds have different bond types ?