Natural transition orbital analyze from TDDFT/TDHF Here is an example. The input file is named c2h4.inp. {{{ $COMPASS Title C2H4 Molecule test run, cc-pvqz Basis 6-31G Geometry C .000000 .000000 .667480 C .000000 .000000 -.667480 H .000000 .922832 1.237695 H .000000 -.922832 1.237695 H .000000 .922832 -1.237695 H .000000 -.922832 -1.237695 End geometry Group C(1) Skeleton $END $xuanyuan Direct Schwartz $end $scf RHF Charge 0 $end # First TDDFT calculate 3 excited states. Notice, keyword "istore" is used to save wavefunction. $TDDFT IMETHOD 1 ISF 0 ITDA 0 IDIAG 1 istore 1 iexit 3 AOKXC MemJKOP 2048 crit_e 1.d-4 $END # Seconded TDDFT is used to carry out NTO analyze. Two states, namely the 1st and 3rd states are asked to perform NTO analyzes. $TDDFT ntoanalyze 2 1 3 $END }}} After the calculation is finished, two files name as "c2h4.nto1.molden" and "c2h4.nto2.molden" are generated that can be visualized by the program molden.