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Final report summary of LDRD 02-LW-022''Quantum Vibrations in Molecules: A New Frontier in Computational Chemistry''

Description: With the trend towards needing information about chemistry at conditions significantly different from 298K and 1 atm., methods need to be developed to generate and interpret this data. This demand for information about chemistry at extreme conditions comes from many fields. The study of atmospheric chemistry requires knowledge of unusual species that are formed when molecules are exposed to ultraviolet radiation. Studying of energetic materials requires knowledge of the thermochemical and structural properties of a myriad of chemical species under a wide range of temperatures. Basic scientific understanding of the very nature of a chemical bond requires detailed information. Studying these problems computationally requires multiple capabilities. The methodology used must provide both high accuracy and computational efficiency. Studying extreme chemistry also suffers from all the challenges of studying chemistry under non-extreme conditions. Therefore, either a new method must be developed or an old method must be applied in an innovative way. The method we have chosen to use is path integral Monte Carlo (PIMC) for the nuclear degrees of freedom and ab initio electronic structure methods for the electronic degrees of freedom. PIMC and ab initio electronic structure are methods of treating the quantum nature of particles. These methods have been chosen, because an accurate treatment requires treating both the electrons and the nuclei as quantum particles. We developed new ''projected'' methods that reduce the computational demands. These methods along with PIMC in general are described in two Journal of Chemical Physics articles (UCRL-JC-144960 and UCRL-JC-147423). This methodology was implemented into a PIMC code developed as part of this LDRD. The code was parallelized in order to utilize the computational resources of LLNL.
Date: January 22, 2004
Creator: Glaesemann, K R
Partner: UNT Libraries Government Documents Department

Quantitative Molecular Thermochemistry Based on Path Integrals

Description: The calculation of thermochemical data requires accurate molecular energies and heat capacities. Traditional methods rely upon the standard harmonic normal mode analysis to calculate the vibrational and rotational contributions. We utilize path integral Monte Carlo (PIMC) for going beyond the harmonic analysis, to calculate the vibrational and rotational contributions to ab initio energies. This is an application and extension of a method previously developed in our group.
Date: March 14, 2005
Creator: Glaesemann, K R & Fried, L E
Partner: UNT Libraries Government Documents Department

Recent Advances in Modeling Hugoniots with Cheetah

Description: We describe improvements to the Cheetah thermochemical-kinetics code's equilibrium solver to enable it to find a wider range of thermodynamic states. Cheetah supports a wide range of elements, condensed detonation products, and gas phase reactions. Therefore, Cheetah can be applied to a wide range of shock problems involving both energetic and non-energetic materials. An improve equation of state is also introduced. New experimental validations of Cheetah's equation of state methodology have been performed, including both reacted and unreacted Hugoniots.
Date: July 26, 2005
Creator: Glaesemann, K R & Fried, L E
Partner: UNT Libraries Government Documents Department

Equation of state for high explosives detonation products with explicit polar and ionic species

Description: We introduce a new thermodynamic theory for detonation products that includes polar and ionic species. The new formalism extends the domain of validity of the previously developed EXP6 equation of state library and opens the possibility of new applications. We illustrate the scope of the new approach on PETN detonation properties and water ionization models.
Date: June 28, 2006
Creator: Bastea, S; Glaesemann, K R & Fried, L E
Partner: UNT Libraries Government Documents Department