AMBER: steered MD

From: Germain Vallverdu <germain.vallverdu.lcp.u-psud.fr>
Date: Wed, 10 Sep 2008 12:26:31 +0200

Hello AMBER !

I am trying to do a steered MD with the following dist.RST file :

# change phi de r2=0 a r2a = 180 degre
&rst iat=21,22,24,25, r2=0., rk2=5000., r2a=180.,  /

But the run stops at the beginning with this error message :

******
 CA2 (   21)-CB2 (   22)-CG2 (   24)-CD1 (   25)    NSTEP1=     0 NSTEP2= 50000
R1 =-100.000 R2 =   0.000 R3 =   0.000 R4 = 100.000 RK2 =5000.000 RK3 = 5000.000
R1A=-100.000 R2A= 180.000 R3A= 180.000 R4A= 100.000 RK2A=   0.000 RK3A=    0.000
 Rcurr:   -0.131  Rcurr-(R2+R3)/2:    0.131  MIN(Rcurr-R2,Rcurr-R3):    0.131
 ERROR: r1 -> r4 (and r1a -> r4a) must be monotonically increasing; Offending restraint:
******
 CA2 (   21)-CB2 (   22)-CG2 (   24)-CD1 (   25)    NSTEP1=     0 NSTEP2= 50000
R1 =-100.000 R2 =   0.000 R3 =   0.000 R4 = 100.000 RK2 =5000.000 RK3 = 5000.000
R1A=-100.000 R2A= 180.000 R3A= 180.000 R4A= 100.000 RK2A=   0.000 RK3A=    0.000

I tried to defined r4a into the dist.RST file but it does not work.

As you saw my coordinate is a dihedral angle and r4a is too small.

Thanks

Germain


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