# Example: CD spectrum, hybrid functional: Twisted ethene¶

Download Twist_Ethene_TDDFT.run

If the subkey CDSPECTRUM is included in the key EXCITATIONS, the rotatory strength is calculated for the calculated excitations, in order to calculate the CD (Circular Dichroism) spectrum. Only useful for chiral molecules. A hybrid functional is used in this case.

With the VELOCITY keyword also the dipole-velocity representation of the rotatory strength is calculated.

Note: results will be physically meaningless due to small basis set. purpose of this job is to provide a test case for the CD implementation

Do not use less strict convergence criteria than default, better to use tighter criteria. The approximations in the evaluation of the integrals one makes with the linear scaling techniques are effectively switched off by setting LINEARSCALING 100 (recommended to use this).

Usage:

\$ADFBIN/adf <<eor
TITLE twisted ethene

COMMENT
purpose of this job is to provide a test case for the CD implementation
with hybrid functionals, and to test the "velocity" keyword
END

XC
hybrid PBE0
END

Basis
Type TZ2P
Core Small
End

ATOMS
C 0.000000 0.000000 0.000000
C -0.000000 -0.000000 1.350716
H 0.565703 -0.745428 -0.540179
H -0.565703 0.745428 -0.540179
H 0.035837 -0.935093 1.890895
H -0.035837 0.935093 1.890895
END

linearscaling 99
excitations
cdspectrum
onlysinglet
velocity
lowest 20
end

numericalquality good

END INPUT
eor