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Dominic P. Guaņa
organicchemistry_01@yahoo.com.ph

I am studying the interaction of urea molecule and nickel atom, i have performed a potential energy scan around the oxygen atom in urea, i have allowed the nickel atom to rotate around it from 90 to 180 degrees, 90 degree from urea's axis of symmetry to 180 degree.

I am expecting that energy will be lower at 180 degree but unexpectedly it is somewhere between 90 to 180 and not even close to 180.

Attach is the image of energy curve of expected result and rsurface result. Need help for this.

Bellow is the input file used.


!============== SCFTYP, NZVAR, MAXIT & SYSTEM ==============
$CONTRL
      !EXETYP=CHECK
      SCFTYP=UHF
      NZVAR=21
      MAXIT=10000
$END

$SYSTEM
      MWORDS=50
      TIMLIM=10000
      FASTF=.T.
      WSCTL=.T.
      L2SIZE=1750
$END


!============== Run Type ==============
$CONTRL
      RUNTYP=RSURFACE
$END


!============== DLC ==============
!-- Automatic generation of internal coordinates --
$ZMAT
      DLC=.T.
      AUTO=.T.
$END

$STATPT
      NOREG=5
      NSTEP=200
      ITBMAT=50
$END


!============== Functional ==============
$CONTRL
      DFTTYP=B3LYP
$END


!============== Basis ==============
$BASIS
      GBASIS=TZV
      NPFUNC=1
      NDFUNC=1
      NFFUNC=1
$END

!============== NONVDW ==============
!-- User defined bond/s --
$ZMAT
      NONVDW(1)=1,9
$END

!============== SURFACE ==============

$SURF
      NDISP1=11
      DISP1=8.98999999
$END

$ZMAT
      IFZMAT(1)=2,2,1,9,1,1,9
      SCAN=.T.
      IFDMOD=2
      AUTOFV=.T.
$END

!============== Geometry ==============
$DATA
Method Proper, Urea, Nickel, Symmetry, RSURFACE
Cs
0.0 1.0 0.0 0.0 0.0 0.0
0.0 0.0 1.0
O     8.0     0.00000000     0.00000000     0.00000000
C     6.0     0.00000000     1.21811247     0.00000000
N     7.0     1.16005301     1.95553017     0.00000000
H     1.0     2.02442145     1.44599521     0.00000000
H     1.0     1.18871176     2.95830655     0.00000000
Ni    28.0     0.00000000    0.00000000    20.00000000
$END

expected and rsurface result