Knowledge Bank

Retrieval of molecular parameters from the highest resolution molecular spectra is complicated by the existence of intramolecular energy $conduits.1-3$ These energy pathways are referred to as accidental resonances and arise due to the model used in the characterization of rotation-vibration energies of gas phase molecules. Highly precise analyses are required to support the studies of planetary atmospheres including that of the earth. Without achieving the results that are the goal of this project, production of precise calculated spectral atlases for molecules such as acetylene and ethane in the 10 micrometer atmospheric window would not be possible. A model including more than 20 interacting vibrational states for a symmetric deuterated halo-fluoride serves as the basis for a case study of the numerical retrieval of molecular parameters. This treatment of inverse eigenvalue problem uses the Hellman-Feynman $Theorem4-6$ to calculate the changes in the molecular energles of the interacting states as a function of the molecular parameters in a necessarily iterative nonlinear least mean square analysis system. Since hundreds of iterations are necessary to converge the system to physically meaningful results, the porting of the system to the vector 3090/200 makes explorations of the system possible. Typical Iteration cycle times run to 15 minutes of cpu time at vectorization levels of from 50 to 70%. A complete analysis, presuming that no more than a few false paths are followed in the process, is estimated to consume 30 to 50 hours of 3090/200E cpu time at approximately 18 to 30 hours of vector facility time (60% vectorization). Performance enhancements of a factor of 40 over a 6 VUP system were achieved.