Re: EWALD

From: Yuguang Mu <ygmu.theochem.uni-frankfurt.de>
Date: Mon, 10 Mar 2003 08:13:31 +0100 (MET)

> It doesn't sound like this should be happening; we would need more details
> (e.g. actual input files) to figure out what is going on. What is your
> value of vdwmeth? If this is turned on, you would get a vdW term, although
> it would not be accurate, since it assumes a continuous density.
>
> ..dac

Here is my input file, just one-step energy calculation, I didnot switch
on the vdwmeth.

# sander: Eqlbrtn of waters const T , SHAKE, cut=12.0
 &cntrl
    irest=0, ntx=1,
    imin=1,
    maxcyc=0,ncyc=100,ntmin=2,
    nstlim=1,
    ntpr=1, ntwr=500,
    t=0.0, dt=0.0020, vlimit=20.0,
    ntt=1, temp0=300.0, dtemp=0.0, tautp=0.2,
    ntb=2, ntp=1, pres0=1.0, comp=44.5, taup=0.5,
    ntc=2, tol=0.0001, ntf=2, nsnb=10,
    cut=9.0,scnb=2.0, scee=1.2,
    ntr=0,
 &end
Group input for restrained atoms
900.0
RES 1 29
END
END

$$$$ And this is the output file (part)

                    FINAL RESULTS



   NSTEP ENERGY RMS GMAX NAME NUMBER
      1 -2.1114E-02 3.7289E-02 5.8693E-02 O 1

 BOND = 0.0000 ANGLE = 0.0000 DIHED =
0.0000
 VDWAALS = -0.0002 EEL = -0.0209 HBOND =
0.0000
 1-4 VDW = 0.0000 1-4 EEL = 0.0000 CONSTRAINT =
0.0000
|
| ELAPSED TIME = 0.250 TOTAL TIME = 0.250


When I change the cut=3.0
The VDWAALS term is larger




   NSTEP ENERGY RMS GMAX NAME NUMBER
      1 -2.1656E+00 4.8310E+00 6.6157E+00 O 1

 BOND = 0.0000 ANGLE = 0.0000 DIHED =
0.0000
 VDWAALS = -0.0058 EEL = -2.1599 HBOND =
0.0000
 1-4 VDW = 0.0000 1-4 EEL = 0.0000 CONSTRAINT =
0.0000
|
Received on Mon Mar 10 2003 - 07:53:01 PST
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