Subject: GAMESS: gradient out of range error

From: Ralf Oestereich <[email-masked]>
Date: Tue, 31 May 94 13:00:29 MESZ

Dear netters,

we have the following problem with GAMESS (US):

While calculating the molecule:

            H3C                    .  Cl
               \                  . 
        Cl.....Si --------------Si xxx Cl
             x                   \ 
          Cl                      CH3

with a 3-21G basis set, using no symmetrie (C1), GAMESS
terminates after a few hours with:

          MAXIMUM GRADIENT =  3.5926839    RMS GRADIENT = 1.1734616
0OPTIMIZATION ABORTED.
    -- GRADIENT OUT OF RANGE
    -- MAXIMUM ALLOWED FORCE (FMAXT) =    1.000
 EXECUTION OF GAMESS TERMINATED ABNORMALLY AT Mon May 30 13:29:14 1994

As input with use coordinates which are optimzed with ALCHEMEY
(PC-Windows Version), and then simply translate them, so that
the first Silicon lies at 0/0/1.52.  At least out input-file:

 $CONTRL SCFTYP=RHF RUNTYP=OPTIMIZE COORD=UNIQUE $END
 $CONTRL PLTORB=.TRUE. MOLPLT=.TRUE. EXETYP=RUN $END
 $SYSTEM TIMLIM=6000 MEMORY=300000 $END
 $BASIS GBASIS=N21 NGAUSS=3 $END
 $GUESS=HUCKEL $END
 $STATPT NSTEP=200 $END
 $DATA
MethylChlor2-Sil-Sil-MethylChlor2  RHF/3-21G, Symmetrie C1
C1
SILICON  14.0      0.0000   0.0000   0.8094
SILICON  14.0      2.2068   0.2512  -0.7219 
CHLOR    17.0     -0.4898  -0.7698  -0.6029 
CARBON    6.0     -0.0041  -0.4822   1.8261 
CARBON    6.0      2.2029   0.9573  -2.4745
CHLOR    17.0      2.7256   0.9298   0.0391
HYDROGEN  1.0      1.6782   1.9252  -2.4824
HYDROGEN  1.0      1.6753   0.2673  -3.1496
HYDROGEN  1.0      3.2307   1.105   -2.843 
HYDROGEN  1.0     -1.0186  -0.6726   2.1871
HYDROGEN  1.0      0.4482   0.3304   2.421 
HYDROGEN  1.0      0.6092  -1.3903   1.9685 
CHLOR    17.0     -0.5346   0.9436  -0.1505 
CHLOR    17.0      2.7156  -0.7913  -0.6104
 $END

What must we change, to calculate the molecule?
Is our basis-set okay?
Why does GAMESS terminate, what does it mean, if the
gradient vector is to big?

I hope someone is able to help us! Please send mail to

[email-masked]

Thanks in advance,
			Ralf