Molcas Forum

1sVishnu_sk

Member

Registered: 2024-10-30

Posts: 5

Internal Coordinates in Slapaf

I cant choose internal coordinates while using slapaf's optimisation. It is showing internal coordinates not defined. I have attached the input file below

&GATEWAY
  coord = DMDS.xyz
  basis = ANO-RCC-VDZ

>>> Export MOLCAS_MAXITER=100
>>> Do while

 &SEWARD
 &SCF ; Title="H2O minimum optimization"; KSDFT=B3LYP
 &SLAPAF
  Internal Coordinates
  b1 = bond S1 S2
  b1= 2.67
  End of Internal
>>> EndDo

Ignacio

Administrator

From: Uppsala

Registered: 2015-11-03

Posts: 1,203

Re: Internal Coordinates in Slapaf

If you want to define internal coordinates, you have to define them all. Is your system diatomic?

An example of internal coordinate definition is the following:

Internal
    CO2  = Bond C1 O2
    OH3  = Bond C1 H3
    OH4  = Bond C1 H4
    OCH3 = Angle O2 C1 H3
    OCH4 = Angle O2 C1 H4
    DH4  = Dihedral H3 O2 C1 H4
  Vary
    rCO2  = 1.0 CO2
    rOH3  = 1.0 OH3
    rOH4  = 1.0 OH4
    aOCH3 = 1.0 OCH3
    aOCH4 = 1.0 OCH4
    tDH4  = 1.0 DH4
End of Internal

If what you want is fixing the distance between two atoms, you should use constraints (in GATEWAY) instead:

Constraints
    r1 = Bond H1 O
  Values
    r1 = 0.80 angstrom
End of Constraints