Example: CV(n)-DFT excitation energies: Formamide¶
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(\(\infty\))-DFT where the molecular orbitals for the particular excitation are optimized (relaxed), which is called the R-CV(\(\infty\))-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.
$ADFBIN/adf <<eor Title Formamide basis Type DZ Core None end Numericalquality good 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 allpoints xc hybrid B3LYP end CVnDFT ITERATION 10 TOLERANCE 0.001 R_CV_DFT & RELAXALPHA 1 RELAXBETA 1 DAMPORBRELAX 0.2 SUBEND END TDA EXACTDENSITY EXCITATION Davidson & A' 2 A'' 2 SUBEND lowest 4 ONLYSING ANALYTICAL TOLERANCE 1e-5 END end input eor