GROMACS version: 2020.2

GROMACS modification: No

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I have tried to use the enforced rotation approach to rotate the N-terminal Domain of the solvated protein. Then, I have received the following error message:

Fatal error:

Number of atoms in file rotref.0.trr (180116) does not match the number of

atoms in rotation group (152)!

Any suggestions? I have been used the following mdp commands:

; Enforced rotation: No or Yes

rotation = Yes

; Output frequency for angle, torque and rotation potential energy for the whole group

rot-nstrout = 10

; Output frequency for per-slab data (angles, torques and slab centers)

rot-nstsout = 10

; Number of rotation groups

rot-ngroups = 1

; Rotation group name

rot-group0 = TM_A_TM_B

; Rotation potential. Can be iso, iso-pf, pm, pm-pf, rm, rm-pf, rm2, rm2-pf, flex, flex-t, flex2, flex2-t

rot-type0 = iso-pf

; Use mass-weighting of the rotation group positions

rot-massw0 = yes

; Rotation vector, will get normalized

rot-vec0 = 0 0 1

; Rotation rate [degree/ps] and force constant [kJ/(mol*nm^2)]
rot-rate0 = 10.0
rot-k0 = 500.0
; Rotation rate [degree/ps] and force constant [kJ/(mol*nm^2)]

rot-rate0 = 10.0

rot-k0 = 500.0

; Slab distance for flexible axis rotation [nm]

rot-slab-dist0 = 1.5

; Minimum value of Gaussian function for the force to be evaluated (for flex* potentials)

rot-min-gauss0 = 0.001

; Value of additive constant epsilon’ [nm^2] for rm2* and flex2* potentials

rot-eps0 = 0.0001

; Fitting method to determine angle of rotation group (rmsd, norm, or potential)

rot-fit-method0 = norm

; For fit type ‘potential’, nr. of angles around the reference for which the pot. is evaluated

rot-potfit-nsteps0 = 21

; For fit type ‘potential’, distance in degrees between two consecutive angles

rot-potfit-step0 = 0.25

What did I do wrong here? Any suggestions?

Thank you in advance.

Masa