Theoretical calculations using density functional theory (DFT) both on semi
empirical and Ab initio levels have been carried out for pyrromethene laser
dye and related compounds (PM-chromophore, PM-4m, PM 546, PM650 PM
567 and PM597). We carried o
ut theoretical calculations using DFT, AM1, TDDFT
and CIS on ground and excited states for the selected laser dye materials,
we obtained the optimized geometry of the molecules, UV, IR spectrum, and
the transition between the ground S0 and the first excited S1 states exclusively,
the HOMO and LUMO states and other properties.