# Example: Numerical Frequencies: NH3¶

Download Freq_NH3.run

#! /bin/sh

# Summary:
# - Frequencies with symmetric displacements
# - Frequencies with Cartesian displacements
# - Isotope effects in the frequencies

# == Frequencies with symmetric displacements ==

# Computation of frequencies by symmetric displacements. The assumed equilibrium
# input structure should be given in Cartesian coordinates.

# The symmetry is determined automatically by the program as C(3v), from the
# input coordinates. During the calculation first symmetric atomic displacements
# are constructed. The number of such displacements in each irreducible
# representation corresponds to the number of frequencies with the corresponding
# symmetry. All displaced geometries within one representation have the same
# symmetry, which enables us to use it to speed up the computation
# significantly.

AMS_JOBNAME=NH3_symm $AMSBIN/ams <<eor System atoms N 0.0000 0.0000 0.0000 H 0.4729 0.8190 0.3821 H -0.9457 0.0000 0.3821 H 0.4729 -0.8190 0.3821 end Symmetrize Yes end Task SinglePoint Properties NormalModes Yes End NormalModes Displacements Symmetric End Thermo Temperatures 300:400:10 End Engine ADF title NH3 frequencies in symmetric displacements BeckeGrid quality good End Basis type TZP core Small End EndEngine eor # == Frequencies with Cartesian displacements == # Computation of frequencies by Cartesian displacements. The assumed equilibrium # input structure is given in internal coordinates. AMS_JOBNAME=NH3_cartesian$AMSBIN/ams <<eor
System
atoms
N  0.0000    0.0000    0.0000
H  0.4729    0.8190    0.3821
H -0.9457    0.0000    0.3821
H  0.4729   -0.8190    0.3821
end
Symmetrize Yes
end

Task SinglePoint

Properties
NormalModes Yes
End

NormalModes
Hessian Numerical
Displacements Cartesian
End

Thermo
Temperatures 300:400:10
End

Engine ADF
title NH3 frequencies
BeckeGrid
quality good
End
Basis
type TZP
core Small
End
EndEngine
eor

# The symmetry is determined automatically by the program as C(3v), from the
# input coordinates. In a Frequencies calculation the symmetry (specified on
# input or computed internally) is used for analysis and in some cases to speed
# up the calculation.

# The equilibrium coordinate values are supplied as identifiers that are
# associated with values in the define block.

# The key thermo addresses the thermodynamical analysis (only available in a
# Frequencies calculation, otherwise ignored). The specification Temperatures 300:400:10
# means that the thermodynamic properties are printed for the temperature range
# 300-400K using 10 equidistant steps and for a pressure of 1.0 atmosphere
# (default).

# Frequencies calculations suffer easily from numerical inaccuracies. Therefore,
# the default numerical integration precision in a Frequencies calculation is
# higher than in an ordinary single-point or minimization run.

# == Isotope effects in the frequencies ==

# Calculate a different isotope of H, in this case deuterium.

AMS_JOBNAME=Isotope \$AMSBIN/ams <<eor
System
atoms
N   0.0000    0.0000    0.0000
H   0.4729    0.8190    0.3821 mass=2.014
H  -0.9457    0.0000    0.3821 mass=2.014
H   0.4729   -0.8190    0.3821 mass=2.014
end
Symmetrize Yes
end

Task SinglePoint

Properties
NormalModes Yes
End

NormalModes
Hessian Numerical
Displacements Cartesian
End

Thermo
Temperatures 300:400:10
End

Engine ADF
title NH3 frequencies
BeckeGrid
quality good
End
Basis
type TZP
core Small
End
EndEngine
eor