[AMBER] QM-MM Equilibration of the System

From: Brittany Boykin <bzb0031.tigermail.auburn.edu>
Date: Mon, 15 Jun 2015 16:11:25 +0000

Hello users,

I am conducting QM-MM using AMBER for my methyltransferase systems. I am having some trouble on the equilibration of the system for pressure and temperature using script eq_pt.csh. I used NSTEP: 50,000, dt= 0.001 with time step of 1fs first after running calculation for volume, script eq_v.csh. I then increased the steps to 500,000 to see is the calculation would converge. In both cases the system did not fully converge, as I keep receiving this Warning, shown below, several times. Also, the calculation completely ran in both cases.

QMMM: Unable to achieve self consistency to the tolerances specified
QMMM: No convergence in SCF after 1000 steps.
QMMM: Job will continue with unconverged SCF. Warning energies
QMMM: and forces for this step will not be accurate.
QMMM: E = -0.8514E+06 DeltaE = 0.1002E+02 DeltaP = 0.1050E+00
QMMM: Smallest DeltaE = 0.2486E+01 DeltaP = 0.6844E-01 Step = 47

How can I fix this problem for each system so that I can continue to umbrella sampling?

Thank you in advance?

Brittany Boykin
Graduate Student
Auburn University
Department of Chemistry and Biochemistry
e: bzb0031.tigermail.auburn.edu
c: (404)545.1036
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Received on Mon Jun 15 2015 - 09:30:02 PDT
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