A hybrid variational-perturbation calculation of the ro-vibrational spectrum of nitric acid.

摘要: Rotation-vibration spectra of the nitric acid molecule, HNO3, are calculated for wavenumbers up to 7000 cm−1. Calculations performed using a Hamiltonian expressed in internal curvilinear vibrational coordinates employing hybrid variational-perturbation method. An initial potential energy surface (PES) and dipole moment function (DMF) ab initio at CCSD(T)/aug-cc-pVQZ level theory. Parameters PES DMF varied minimize differences between experimental transition frequencies intensities. The average, absolute deviation values is 0.2 cm−1 fundamental bands 0.4 those first overtone lowest combination bands. For intensities, differ by 0.3% 40% fundamentals overtones, respectively. optimized used calculate room-temperature ro-vibrational spectrum. These calculation reproduce both form absorption fine details observed spectra, including rotational structure numerous hot band. Many these found be missing from compilation HITRAN. A room temperature line list comprising 2 × 109 lines computed.