Meteor Entry and Breakup Based on Evolution of NASAs Entry Capsule Design Tools
No abstract available
Prabhu, Dinesh↗
Engineering topics
Bauschlicher, Charles
Publications and source records attributed to Bauschlicher, Charles.
IR Spectra and Bond Energies Computed Using DFT
The combination of density functional theory (DFT) frequencies and infrared (IR) intensities and experimental spectra is a very powerful tool in the identification of molecules and ions. The computed and measured isotopic ratios make the identification much more secure than frequencies and intensities alone. This will be illustrated using several examples, such as Mn(CO)n and Mn(CO)n-. The accuracy of DFT metal-ligand bond energies will also be discussed.
Bauschlicher, Charles↗
The Effect of the Weight Scheme on DFT Vibrational Frequencies
All-electron B3LYP harmonic frequencies of Ge2H5 and Ge2H6 are computed for several choices of grid and using both the Becke and the Stratmann, Scuseria, and Frisch atomic partition functions (weight scheme). For large grids, the results are independent of the weighting scheme. The lowest frequency mode is much more stable with respect to the number of grid points when the Stratmann, Scuseria, and Frisch weights are used.
Bauschlicher, Charles↗
Theoretical Studies of the Quasi-Bound Vibrational Levels in the B State of CH3
Consider the calculation of the oscillator strength of th B yielded by X electronic transition in CH3. The X state is strongly bound, but in the B state, CH3 is pre-dissociated by H atom tunneling through a potential energy barrier to form CH2+H. If we turn off pre-dissociation by making the potential outside of the barrier repulsive, the calculated 0-0 oscillator strength for CD3 from high quality ab initio potential and transition moment data along with accurate ro-vibrational wavefunctions is 0.0212, which is a factor of two greater than experiment. This discrepancy is largely due to the neglect of pre-dissociation. In this poster we explore techniques for including pre-dissociation in the calculations.
Schwenke, David W.↗
Theoretical study of thermodynamic properties and reaction rates of importance in the high-speed research program
One of the primary goals of NASA's high-speed research program is to determine the feasibility of designing an environmentally safe commercial supersonic transport airplane. The largest environmental concern is focused on the amount of ozone destroying nitrogen oxides (NO(x)) that would be injected into the lower stratosphere during the cruise portion of the flight. The limitations placed on NO(x) emission require more than an order of magnitude reduction over current engine designs. To develop strategies to meet this goal requires first gaining a fundamental understanding of the combustion chemistry. To accurately model the combustor requires a computational fluid dynamics approach that includes both turbulence and chemistry. Since many of the important chemical processes in this regime involve highly reactive radicals, an experimental determination of the required thermodynamic data and rate constants is often very difficult. Unlike experimental approaches, theoretical methods are as applicable to highly reactive species as stable ones. Also our approximation of treating the dynamics classically becomes more accurate with increasing temperature. In this article we review recent progress in generating thermodynamic properties and rate constants that are required to understand NO(x) formation in the combustion process. We also describe our one-dimensional modeling efforts to validate an NH3 combustion reaction mechanism. We have been working in collaboration with researchers at LeRC, to ensure that our theoretical work is focused on the most important thermodynamic quantities and rate constants required in the chemical data base.
Langhoff, Stephen↗