MOLCAS Gateway program
 
The Gateway module collects information about molecular system (geometry, basis sets, symmetry) to be used for future calculations. It destroys the runfile so you should use it outside any optimisation loops.
 
The Gateway program uses a subset of the input to Seward, all the keywords for Gateway can also be used for Seward.
 
As an example of how Gateway can be used I have put 2 input files below. The first is with using Gateway and in the second I just use Seward. Both calculations are performing the same calculation with the same options and parameters.
 
Note the shorter notation of the basisset used. Also note that after the COORD keyword the number 6 denotes the 6 atoms and the empty line after that is a requirement.
 
Input using Gateway

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&GATEWAY &END
COORD
6
 
H1            -1.224928        0.911425        0.000000 Angstrom
H2            -1.224928       -0.911425        0.000000 Angstrom
H3             1.224928        0.911425        0.000000 Angstrom
H4             1.224928       -0.911425        0.000000 Angstrom
C1            -0.657464        0.000000        0.000000 Angstrom
C2             0.657464        0.000000        0.000000 Angstrom
BASIS
6-31G**
End of Input
 
 &SEWARD &END
Title
C2H4
End of input
 
 &SCF &END
Title
C2H2
Charge
0
End of input

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Input without using Gateway

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 &SEWARD &END
Title
C2H4
Basis set
H.3-21G.Binkley.3s.2s..
H1            -1.224928        0.911425        0.000000 Angstrom
H2            -1.224928       -0.911425        0.000000 Angstrom
H3             1.224928        0.911425        0.000000 Angstrom
H4             1.224928       -0.911425        0.000000 Angstrom
End of basis
Basis set
C.3-21G.Binkley.6s3p.3s2p..
C1            -0.657464        0.000000        0.000000 Angstrom
C2             0.657464        0.000000        0.000000 Angstrom
End of basis
End of input
 
 &SCF &END
Title
C2H4
Charge
0
End of input
 

MOLCAS z-matrix input
 
In Gateway z-matrix input can be given. For example the following input is for ethene:
 

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 &GATEWAY &END
ZMAT
C.3-21G.Binkley.6s3p.3s2p..
H.3-21G.Binkley.3s.2s..
End of basis
C1
C2 1 1.316454
H1 1 1.076402 2 121.742
H2 1 1.076402 2 121.742 3 180.000
H3 2 1.076402 1 121.742 3   0.000
H4 2 1.076402 1 121.742 3 180.000
End of z-matrix
End of Input

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