Exploring the Excited-State Nonadiabatic Effects in the Semisaturated Planar Tetracoordinated Carbon Molecule C₇H₄

Abstract

We theoretically study the nonadiabatic relaxation dynamics of low-lying singlet excited-states of semisaturated planar tetracoordinated carbon molecule, C7H4. This molecule possesses a stable C2v ground-state equilibrium geometry. The three low-lying singlet states, S1, S2 and S3, lie in the energy gap of about 1.2 eV. The potential energy surfaces constructed within the quadratic vibronic coupling formalism reveal multiple conical intersections in the Franck-Condon region. Upon photoexcitation to S3, the wavepacket decays rapidly to lower states via these conical intersections. We also observe the wavepacket transfer to S3 during the initial wavepacket evolution on lower states, suggesting the nonadiabatic behavior of photoexcited planar C7H4.

Keywords

• excited-states
• nonadiabatic dynamics
• relaxation pathways