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Search Publications by: Karl K. Irikura (Fed)

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Displaying 26 - 50 of 106

Obtaining Molecular Thermochemistry From Calculations

September 30, 2007
Author(s)
Karl K. Irikura
There are several computational approaches for predicting gas-phase, molecular thermochemistry. For common organic compounds, empirical methods are quick to compute and have been effectively parameterized. For uncommon compounds, the relative robustness of

Experimental Vibrational Zero-Point Energies: Diatomic Molecules

April 18, 2007
Author(s)
Karl K. Irikura
Vibrational zero-point energies (ZPEs), as determined from published spectroscopic constants, are derived for 85 diatomic molecules. Standard uncertainties are also provided, including estimated contributions from bias as well as the statistical

Is NO 3 Formed During the Decomposition of Nitramine Explosives?

December 21, 2006
Author(s)
Karl K. Irikura, Russell D. Johnson III
Quantum chemistry calculations reveal that it is both thermodynamically and kinetically reasonable to produce NO3 (nitrate radical) during the thermal decomposition of RDX (1,3,5-trinitrohexahydro-s-triazine) and other nitramines. However, experimental

Uncertainties in Scaling Factors for ab Initio Vibrational Frequencies

September 1, 2005
Author(s)
Karl K. Irikura, Russell D. Johnson III, Raghu N. Kacker
Vibrational frequencies determined from ab initio calculations are often scaled by empirical factors. An empirical scaling factor partially compensates for the errors arising from vibrational anharmonicity and incomplete treatment of electron correlation

Ab Initio Characterization of the Weakly Bound Anions ClOO- and ArCl-

August 1, 2003
Author(s)
Karl K. Irikura
Experimental studies of the energetics and vibrational spectrum of the chloroperoxyl radical, ClOO, are contradictory. The most recent experiment accessed the radical by photodetachment of the corresponding anion, ClOO -. The present study uses both multi-

Electron-Impact Total Ionization Cross-Sections of the Chlorofluoromethanes

January 1, 2003
Author(s)
Karl K. Irikura, M A. Ali, Yong Sik Kim
Electron-impact total ionization cross sections for CCl 3F (Freon 11), CCl 2F 2 (Freon 12), CClF 3 (Freon 13), CHCl 2F (Freon 21), CHClF 2 (Freon 22), and CH 2ClF (Freon 31) are calculated using the Binary-Encounter-Bethe (BEB) theoretical model. The BEB

New Empirical Procedures for Improving Ab Initio Energetics

October 1, 2002
Author(s)
Karl K. Irikura
Empirical schemes are developed for correcting the energies resulting from a moderately high-level abinitio calculation. Each method involves only a few adjustable parameters, which are determined by fitting a set of 31 high-spin atomization energies

Electron-Impact Total Ionization Cross Sections of Hydrocarbon Ions

February 1, 2002
Author(s)
Karl K. Irikura, Yong Sik Kim, M A. Ali
The Binary-Encounter-Bethe (BEB) model for electron-impact total ionization cross sections has been applied to CH 2 +, CH 3 +, CH 4 +, C 2H 2 +, C 2H 4 +, C 2H 6 +, and H 3O +. The cross sections for the hydrocarbon ions are needed for modeling cool