# Example: CV(n)-DFT excitation energies: Formamide¶

```
#!/bin/sh
# Calculation of the excitation energies of Formamide using the CV(n)-DFT
# method. Due to bugs in older versions it is important to use ADF2016.105 or
# later.
# Example of CV(infinity)-DFT where the molecular orbitals for the particular
# excitation are optimized (relaxed), which is called the R-CV(infinity)-DFT method.
# In this case, the transition U-vector is frozen, while the orbitals are
# relaxed. ALLPOINTS should be used in case of a symmetric molecule.
# EXACTDENSITY should be used for precision reasons. Note that the irrep labels
# for C(s) symmetry that are used in the excitation code (A' and A'') differ
# from those that are used during the SCF (AA and AAA). The example contains of
# 2 parts. In the first example singlet-singlet excitations are calculated using
# the subkeyword ONLYSING in the EXCITATIONS block key. In the second example
# singlet-triplet excitations are calculated replacing the subkeyword ONLYSING
# with the subkeyword ONLYTRIP in the EXCITATIONS block key.
AMS_JOBNAME=SS $AMSBIN/ams <<eor
System
atoms
H -0.927427 -0.600301 0.000000
H 1.070498 -1.782390 0.000000
H 2.024514 -0.325050 0.000000
C 0.000000 0.000000 0.000000
O 0.000000 1.225060 0.000000
N 1.119392 -0.775069 0.000000
end
end
Task SinglePoint
Engine ADF
allpoints
cvndft
iteration 10
r_cv_dft &
damporbrelax 0.2
relaxalpha 1
relaxbeta 1
end
tolerance 0.001
end
exactdensity
excitations
analytical
davidson
A' 2
A'' 2
end
lowest 4
onlysing
tolerance 1e-5
end
basis
core None
fittype ZORA/QZ4P
type DZ
end
numericalquality good
tda
title Formamide
xc
hybrid B3LYP
end
EndEngine
eor
AMS_JOBNAME=ST $AMSBIN/ams <<eor
System
atoms
H -0.927427 -0.600301 0.000000
H 1.070498 -1.782390 0.000000
H 2.024514 -0.325050 0.000000
C 0.000000 0.000000 0.000000
O 0.000000 1.225060 0.000000
N 1.119392 -0.775069 0.000000
end
end
Task SinglePoint
Engine ADF
allpoints
cvndft
iteration 10
r_cv_dft &
damporbrelax 0.2
relaxalpha 1
relaxbeta 1
end
tolerance 0.001
end
exactdensity
excitations
analytical
davidson
A' 2
A'' 2
end
lowest 4
onlytrip
tolerance 1e-5
end
basis
core None
fittype ZORA/QZ4P
type DZ
end
numericalquality good
tda
title Formamide
xc
hybrid B3LYP
end
EndEngine
eor
```