AMBER Archive (2004)

Subject: Re: AMBER: antechamber + FAILED TO ACHIEVE SCF

From: David A. Case (case_at_scripps.edu)
Date: Mon Feb 09 2004 - 16:17:49 CST

On Mon, Feb 09, 2004, Junmei Wang wrote:
>
> I would like to recommend to optimize the input structure with other
> programs, such as sybyl and/or apply another conformation. The input
> structure should be quite "reasonable". The neat thing for AM1 charges lie
> that they are not or slightly conformation-dependent.

This does not seem to be the problem here, as far as I can tell. The
mopac calculation gets very close to the final correct energy (within
0.1 kcal/mol), but then moves to a "final" step where "All convergers are now
forced off"; this final step fails to converge. Furthermore, this last
step appears to be new to mopac510mn -- it was not present in the mopac509mn
runs. Plus this is a test case (guanine) with a pretty good initial
structure. But I don't know what to do in this case--do other antechamber
test cases work?

>
> CYCLE: 35 TIME: 0.1 TIME LEFT: 3594.1 GRAD.: 12.037 HEAT:-82.68366
> CYCLE: 36 TIME: 0.2 TIME LEFT: 3593.9 GRAD.: 15.773 HEAT:-82.71233

(mopac509mn gives a final energy of -82.78)
> 0TEST ON X SATISFIED
> HOWEVER, A COMPONENT OF GRADIENT IS LARGER THAN 0.10
>
> THERE HAVE BEEN 3 ATTEMPTS TO REDUCE THE GRADIENT.
> DURING THESE ATTEMPTS THE ENERGY DROPPED BY LESS THAN 0.3000
> KCAL/MOLE
> FURTHER CALCULATION IS NOT JUSTIFIED AT THIS POINT.
>
>
> ALL CONVERGERS ARE NOW FORCED ON
> SHIFT=10, PULAY ON, CAMP-KING ON
> AND ITERATION COUNTER RESET
>
> """""""""""""UNABLE TO ACHIEVE SELF-CONSISTENCE 

-- 

==================================================================
David A. Case                     |  e-mail:      case_at_scripps.edu
Dept. of Molecular Biology, TPC15 |  fax:          +1-858-784-8896
The Scripps Research Institute    |  phone:        +1-858-784-9768
10550 N. Torrey Pines Rd.         |  home page:                   
La Jolla CA 92037  USA            |    http://www.scripps.edu/case
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