Nonlinear optical response of α -terpinolene and β -phellandrene chromophores: An octupolar gas-to-solvent enhancement able to retain light conduction

The search for new materials with improved nonlinear optical (NLO) response is a field of growing interest in materials science. Typically, the dipole ΦJ=1 contributions exceed the octupolar ΦJ=3 ones and dominate the optical behavior. However, the latter is essential for NLO device engineering. Under this scenario, this work investigates the electronic-optical properties of the α-terpinolene and β-phellandrene molecules within the Hyper-Rayleigh scattering formalism (HRS). It includes solvent contributions using a sequential Monte Carlo/Quantum Mechanics procedure. According to Density Functional Theory analysis, molecular solvatochromism acts differently for the two chromophores. While α-terpinolene undergoes a hypsochromic effect, the β-phellandrene molecule shows moderate bathochromism, both with a strong absorption band in the ultraviolet region (λmax