CH₄: Analytic Frequencies

Sample directory: adf/CH4_SecDeriv/

In this example, we use a new feature of adf2006.01: geometry optimization immediately followed by calculation of frequencies. This is done by specifying the Geometry and AnalyticalFreq input blocks in one file.

Note: when using this feature, one should generally set the integration accuracy to a value appropriate for the frequencies calculation, which is about 5.0. In order to save time we neglect the recommendation in this example.

$ADFBIN/adf << eor
title CH4 LDA potential

Define
 ZERO = 0.0
 RCH = 1.0850
 DCH = sqrt(3)*(RCH/3)
End

Atoms
 C  0.0  0.0  0.0
 H  DCH -DCH  DCH
 H  DCH  DCH -DCH
 H -DCH  DCH  DCH
 H -DCH -DCH -DCH
End

Basis
 Type TZP
 Core None
End

integration 4.0

Geometry
  Optim all
  converge grad=0.0001
End

AnalyticalFreq
End

End input
eor