Calculations of n→π* Transition Energies

Azarias, Cloe

Calculations of n→π* Transition Energies : comparisons between TD-DFT, ADC, CC, CASPT2, and BSE/GW descriptions / Cloé Azarias ... [et al.]. -- Using a large panel of theoretical approaches, namely, CC2, CCSD, CCSDR(3), CC3, ADC(2), ADC(3), CASPT2, time-dependent density functional theory (TD-DFT), and BSE/evGW, the two latter combined with different exchange-correlation functionals, we investigate the lowest singlet transition in 23 n ->pi* compounds based on the nitroso, thiocarbonyl, carbonyl, and diazo chromophores. First, for 16 small derivatives we compare the transition energies provided by the different wave function approaches to define theoretical best estimates. For this set, it surprisingly turned out that ADC(2) offers a better match with CC3 than ADC(3). Next, we use 10 functionals belonging to the "LYP" and "M06" families and compare the TD-DFT and the BSE/evGW descriptions. The BSE/evGW results are less sensitive than their TD-DFT counterparts to the selected functional, especially in the M06 series. Nevertheless, BSE/evGW delivers larger errors than TD-CAM-B3LYP, which provides extremely accurate results in th

In The Journal of Physical Chemistry A. -- Washington : The American Chemical Society, 2017. -- ISSN 1089-5639. -- ISSN 1520-5215. -- Vol. 121, no. 32 (2017), pp. 6122-6134