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Semiclassical (SC) Description of Electronically Non-AdiabaticDynamics via the Initial Value Representation (IVR)

Description: The initial value representation (IVR) of semiclassical (SC) theory is used in conjunction with the Meyer-Miller/Stock-Thoss description of electronic degrees of freedom in order to treat electronically non-adiabatic processes. It is emphasized that the classical equations of motion for the nuclear and electronic degrees of freedom that emerge in this description are precisely the Ehrenfest equations of motion (the force on the nuclei is the force averaged over the electronic wavefunction), but that the trajectories given by these equations of motion do not have the usual shortcomings of the traditional Ehrenfest model when they are used within the SC-IVR framework. For example, in the traditional Ehrenfest model (a mixed quantum-classical approach) the nuclear motion emerges from a non-adiabatic encounter on an average potential energy surface (a weighted average according to the population in the various electronic states), while the SC-IVR describes the correct correlation between electronic and nuclear dynamics, i.e., the nuclear motion is on one potential energy surface or the other depending on the electronic state. Calculations using forward-backward versions of SC-IVR theory (FB-IVR) are presented to illustrate this behavior. An even more approximate version of the SC-IVR, the linearized approximation (LSC-IVR), is slightly better than the traditional Ehrenfest model, but since it cannot describe quantum coherence effects, the LSC-IVR is also not able to describe the correct correlation between nuclear and electronic dynamics.
Date: June 22, 2007
Creator: Ananth, V.; Venkataraman, C. & Miller, W.H.
Partner: UNT Libraries Government Documents Department

Isolated Sub-Dehumidification Strategies in Large Supermarkets and Grocery Stores

Description: The objective of this project was to determine the potential energy savings associated with reducing the relative humidity in the vicinity of refrigerated display cases in supermarkets, as compared to the widely accepted current practice of maintaining a relatively higher and uniform humidity level throughout the entire supermarket. Existing and new strategies for maintaining lower relative humidity levels near the vicinity of refrigerated display cases were analyzed to determine their effectiveness and limits of application.
Date: October 1, 2011
Creator: Fricke, Brian A. & Sharma, Vishaldeep
Partner: UNT Libraries Government Documents Department

Electronically Nonadiabatic Dynamics via Semiclassical Initial Value Methods

Description: In the late 1970's Meyer and Miller (MM) [J. Chem. Phys. 70, 3214 (1979)] presented a classical Hamiltonian corresponding to a finite set of electronic states of a molecular system (i.e., the various potential energy surfaces and their couplings), so that classical trajectory simulations could be carried out treating the nuclear and electronic degrees of freedom (DOF) in an equivalent dynamical framework (i.e., by classical mechanics), thereby describing non-adiabatic dynamics in a more unified manner. Much later Stock and Thoss (ST) [Phys. Rev. Lett. 78, 578 (1997)] showed that the MM model is actually not a 'model', but rather a 'representation' of the nuclear-electronic system; i.e., were the MMST nuclear-electronic Hamiltonian taken as a Hamiltonian operator and used in the Schroedinger equation, the exact (quantum) nuclear-electronic dynamics would be obtained. In recent years various initial value representations (IVRs) of semiclassical (SC) theory have been used with the MMST Hamiltonian to describe electronically non-adiabatic processes. Of special interest is the fact that though the classical trajectories generated by the MMST Hamiltonian (and which are the 'input' for an SC-IVR treatment) are 'Ehrenfest trajectories', when they are used within the SC-IVR framework the nuclear motion emerges from regions of non-adiabaticity on one potential energy surface (PES) or another, and not on an average PES as in the traditional Ehrenfest model. Examples are presented to illustrate and (hopefully) illuminate this behavior.
Date: December 11, 2008
Creator: Miller, William H.
Partner: UNT Libraries Government Documents Department

Computational studies of the potential energy surface for O(¹D) + H₂S: Characterization of pathways involving H₂SO, HOSH, and H₂OS

Description: Article on computational studies of the potential energy surface for O(¹D) + H₂S and the characterization of pathways involving H₂SO, HOSH, and H₂OS.
Date: December 1, 1994
Creator: Goumri, Abdellatif; Rocha, John-David Ray; Laakso, Dianna; Smith, C. E. & Marshall, Paul
Partner: UNT College of Arts and Sciences

Studies in Chemical Dynamics

Description: This final report draws together the research carried from February, 1986 through January, 2003 concerning a series of topics in chemical dynamics. The specific areas of study include molecular collisions, chemical kinetics, data inversion to extract potential energy surfaces, and model reduction of complex kinetic systems.
Date: June 27, 2003
Creator: Rabitz, Herschel & Ho, Tak-San
Partner: UNT Libraries Government Documents Department

Analysis of Potential Energy Saving and CO2 Emission Reduction of Home Appliances and Commercial Equipments in China

Description: China has implemented a series of minimum energy performance standards (MEPS) for over 30 appliances, voluntary energy efficiency label for 40 products and a mandatory energy information label that covers 19 products to date. However, the impact of these programs and their savings potential has not been evaluated on a consistent basis. This paper uses modeling to estimate the energy saving and CO{sub 2} emission reduction potential of the appliances standard and labeling program for products for which standards are currently in place, under development or those proposed for development in 2010 under three scenarios that differ in the pace and stringency of MEPS development. In addition to a baseline 'Frozen Efficiency' scenario at 2009 MEPS level, the 'Continued Improvement Scenario' (CIS) reflects the likely pace of post-2009 MEPS revisions, and the likely improvement at each revision step. The 'Best Practice Scenario' (BPS) examined the potential of an achievement of international best practice efficiency in broad commercial use today in 2014. This paper concludes that under 'CIS', cumulative electricity consumption could be reduced by 9503 TWh, and annual CO{sub 2} emissions of energy used for all 37 products would be 16% lower than in the frozen efficiency scenario. Under a 'BPS' scenario for a subset of products, cumulative electricity savings would be 5450 TWh and annual CO{sub 2} emissions reduction of energy used for 11 appliances would be 35% lower.
Date: April 1, 2011
Creator: Zhou, Nan; Fridley, David; McNeil, Michael; Zheng, Nina; Letschert, Virginie & Ke, Jing
Partner: UNT Libraries Government Documents Department

THREE AND FOUR CENTER ELIMINATION OF HC1 IN THE MULTIPHOTON DISSOCIATION OF HALOGENATED HYDROCARBONS

Description: Three and four center unimolecular elimination reactions of HCl have been investigated for CHF{sub 2}Cl, CHFCL{sub 2}, CH{sub 3}CCl{sub 3}, CH{sub 3}CF{sub 2}Cl and in a molecular beam experiment using infrared multiphoton absorption to energize the molecule. The translational energy distributions obtained in this work show that the average translational energy released to the fragments is around 8-12 kcal/mole, except for the three center elimination reaction from CHClCF{sub 2}, which gives a value of 1 kcal/mole. In four center eliminations, the translational energy released is less than 20% of the potential energy barrier of the back reaction. This is somewhat less than previous indications that approximately 30% of the potential energy barrier of the exit channel in four center reactions should be released into translation.
Date: April 1, 1978
Creator: Sudbo, Aa. S.; Schulz, P.A.; Shen, Y.R. & Lee, Y.T.
Partner: UNT Libraries Government Documents Department

Graphene Layer Growth Chemistry: Five-Six-Ring Flip Reaction

Description: A theoretical study revealed a new reaction pathway, in which a fused five and six-membered ring complex on the zigzag edge of a graphene layer isomerizes to reverse its orientation, or 'flips,' after activation by a gaseous hydrogen atom. The process is initiated by hydrogen addition to or abstraction from the surface complex. The elementary steps of the migration pathway were analyzed using density-functional theory (DFT) calculations to examine the region of the potential energy surface associated with the pathway. The DFT calculations were performed on substrates modeled by the zigzag edges of tetracene and pentacene. Rate constants for the flip reaction were obtained by the solution of energy master equation utilizing the DFT energies, frequencies, and geometries. The results indicate that this reaction pathway is competitive with other pathways important to the edge evolution of aromatic species in high temperature environments.
Date: March 24, 2007
Creator: Whitesides, Russell; Domin, Dominik; Lester Jr., William A. & Frenklach, Michael
Partner: UNT Libraries Government Documents Department

Graphene Layer Growth: Collision of Migrating Five-MemberRings

Description: A reaction pathway is explored in which two cyclopenta groups combine on the zigzag edge of a graphene layer. The process is initiated by H addition to a five-membered ring, followed by opening of that ring and the formation of a six-membered ring adjacent to another five-membered ring. The elementary steps of the migration pathway are analyzed using density functional theory to examine the region of the potential energy surface associated with the pathway. The calculations are performed on a substrate modeled by the zigzag edge of tetracene. Based on the obtained energetics, the dynamics of the system are analyzed by solving the energy transfer master equations. The results indicate energetic and reaction-rate similarity between the cyclopenta combination and migration reactions. Also examined in the present study are desorption rates of migrating cyclopenta rings which are found to be comparable to cyclopenta ring migration.
Date: December 2, 2005
Creator: Whitesides, Russell; Kollias, Alexander C.; Domin, Dominik; Lester Jr., William A. & Frenklach, Michael
Partner: UNT Libraries Government Documents Department

2010 Atomic & Molecular Interactions Gordon Research Conference

Description: The Atomic and Molecular Interactions Gordon Conferences is justifiably recognized for its broad scope, touching on areas ranging from fundamental gas phase and gas-condensed matter collision dynamics, to laser-molecule interactions, photophysics, and unimolecular decay processes. The meeting has traditionally involved scientists engaged in fundamental research in gas and condensed phases and those who apply these concepts to systems of practical chemical and physical interest. A key tradition in this meeting is the strong mixing of theory and experiment throughout. The program for 2010 conference continues these traditions. At the 2010 AMI GRC, there will be talks in 5 broadly defined and partially overlapping areas of intermolecular interactions and chemical dynamics: (1) Photoionization and Photoelectron Dynamics; (2) Quantum Control and Molecules in Strong Fields; (3) Photochemical Dynamics; (4) Complex Molecules and Condensed Phases; and (5) Clusters and Reaction Dynamics. These areas encompass many of the most productive and exciting areas of chemical physics, including both reactive and nonreactive processes, intermolecular and intramolecular energy transfer, and photodissociation and unimolecular processes. Gas phase dynamics, van der Waals and cluster studies, laser-matter interactions and multiple potential energy surface phenomena will all be discussed.
Date: July 23, 2010
Creator: Martinez, Todd
Partner: UNT Libraries Government Documents Department

Dissociative electron attachment to the H2O molecule II: nucleardynamics on coupled electronic surfaces within the local complexpotential model

Description: We report the results of a first-principles study of dissociative electron attachment (DEA) to H{sub 2}O. The cross sections were obtained from nuclear dynamics calculations carried out in full dimensionality within the local complex potential model by using the multi-configuration time-dependent Hartree method. The calculations employ our previously obtained global, complex-valued, potential energy surfaces for the three ({sup 2}B{sub 1}, {sup 2}A{sub 1}, and {sup 2}B{sub 2}) electronic Feshbach resonances involved in this process. These three metastable states of H{sub 2}O{sup -} undergo several degeneracies, and we incorporate both the Renner-Teller coupling between the {sup 2}B{sub 1} and {sup 2}A{sub 1} states, as well as the conical intersection between the {sup 2}A{sub 1} and {sup 2}B{sub 2} states, into our treatment. The nuclear dynamics are inherently multi-dimensional and involve branching between different final product arrangements as well as extensive excitation of the diatomic fragment. Our results successfully mirror the qualitative features of the major fragment channels observed, but are less successful in reproducing the available results for some of the minor channels. We comment on the applicability of the local complex potential model to such a complicated resonant system.
Date: December 21, 2006
Creator: Haxton, Daniel J.; Rescigno, Thomas N. & McCurdy, C. William
Partner: UNT Libraries Government Documents Department

Waste Heat Recapture from Supermarket Refrigeration Systems

Description: The objective of this project was to determine the potential energy savings associated with improved utilization of waste heat from supermarket refrigeration systems. Existing and advanced strategies for waste heat recovery in supermarkets were analyzed, including options from advanced sources such as combined heat and power (CHP), micro-turbines and fuel cells.
Date: November 1, 2011
Creator: Fricke, Brian A
Partner: UNT Libraries Government Documents Department

Defrost Temperature Termination in Supermarket Refrigeration Systems

Description: The objective of this project was to determine the potential energy savings associated with implementing demand defrost strategies to defrost supermarket refrigerated display case evaporators, as compared to the widely accepted current practice of controlling display case defrost cycles with a preset timer. The defrost heater energy use of several representative display case types was evaluated. In addition, demand defrost strategies for refrigerated display cases as well as those used in residential refrigerator/freezers were evaluated. Furthermore, it is anticipated that future work will include identifying a preferred defrost strategy, with input from Retail Energy Alliance members. Based on this strategy, a demand defrost system will be designed which is suitable for supermarket refrigerated display cases. Limited field testing of the preferred defrost strategy will be performed in a supermarket environment.
Date: November 1, 2011
Creator: Fricke, Brian A & Sharma, Vishaldeep
Partner: UNT Libraries Government Documents Department

Dynamic heat capacity of the east model and of a bead-spring polymer model.

Description: In this report we have presented a brief review of the glass transition and one means of characterizing glassy materials: linear and nonlinear thermodynamic oscillatory experiments to extract the dynamic heat capacity. We have applied these methods to the east model (a variation of the Ising model for glass forming systems) and a simple polymeric system via molecular dynamics simulation, and our results match what is seen in experiment. For the east model, since the dynamics are so simple, a mathematical model is developed that matches the simulated dynamics. For the polymeric system, since the system is a simulation, we can instantaneously 'quench' the system - removing all vibrational energy - to separate the vibrational dynamics from dynamics associated with particle rearrangements. This shows that the long-time glassy dynamics are due entirely to the particle rearrangements, i.e. basin jumping on the potential energy landscape. Finally, we present an extension of linear dynamic heat capacity to the nonlinear regime.
Date: October 1, 2011
Creator: McCoy, John Dwane (New Mexico Institute of Mining and Technology, Socorro, NM); Brown, Jonathan R. (New Mexico Institute of Mining and Technology, Socorro, NM) & Adolf, Douglas Brian
Partner: UNT Libraries Government Documents Department

Wakefields in the LCLS Undulator Transitions

Description: For a short bunch in an elliptical collimator we demonstrate that, as in a purely round collimator, the wake can be estimated from the primary fields of the beam alone. We obtain the wakes in the LCLS rectangular-to-round, undulator transitions using a hybrid method that includes indirect numerical (field) integration and an analytical potential energy term. For the LCLS 1 nC bunch charge configuration, we find the wake-induced energy change in the transitions to be small compared to that due to the resistance of the beam pipe walls.
Date: July 17, 2006
Creator: Bane, K.L.F.; /SLAC; Zagorodov, I. & /DESY
Partner: UNT Libraries Government Documents Department

Michigan State Code Adoption Analysis: Cost-Effectiveness of Lighting Requirements - ASHRAE/IESNA 90.1-2004

Description: This report documents PNNL's analysis of the potential energy effect and cost-effectiveness of the lighting requirements in ASHRAE/IESNA 90.1-2004 if this energy code is adopted in the state of Michigan, instead of the current standard.
Date: September 29, 2006
Creator: Richman, Eric E.
Partner: UNT Libraries Government Documents Department

Building Energy Audit Report for Camp Smith, HI

Description: A detailed energy assessment was performed by a team of engineers from Pacific Northwest National Laboratory (PNNL) under contract to the Department of Energy/Federal Energy Management program (FEMP). The effort used the Facility Energy Decision System (FEDS) model to determine how energy is consumed at Camp Smith, identify the most cost-effective energy retrofit measures, and calculate the potential energy and cost savings. This report documents the results of that assessment.
Date: September 30, 2010
Creator: Chvala, William D.; De La Rosa, Marcus I.; Brown, Daryl R. & Dixon, Douglas R.
Partner: UNT Libraries Government Documents Department

Building Energy Audit Report for Pearl Harbor, HI

Description: A building energy audit was performed by a team of engineers from Pacific Northwest National Laboratory (PNNL) under contract to the Department of Energy/Federal Energy Management Program (FEMP). The effort used the Facility Energy Decision System (FEDS) model to determine how energy is consumed at selected Pearl Harbor buildings, identify cost-effective energy retrofit measures, and calculate the potential energy and cost savings. This report documents the findings of that assessment.
Date: September 30, 2010
Creator: Brown, Daryl R.; Chvala, William D.; De La Rosa, Marcus I. & Dixon, Douglas R.
Partner: UNT Libraries Government Documents Department

Building Energy Audit Report, for Hickam AFB, HI

Description: A building energy assessment was performed by a team of engineers from Pacific Northwest National Laboratory (PNNL) under contract to the Department of Energy/Federal Energy Management program (FEMP). The effort used the Facility Energy Decision System (FEDS) model to determine how energy is consumed at Hickam AFB, identify the most cost-effective energy retrofit measures, and calculate the potential energy and cost savings. This documents reports the results of that assessment.
Date: September 30, 2010
Creator: Chvala, William D.; De La Rosa, Marcus I.; Brown, Daryl R. & Dixon, Douglas R.
Partner: UNT Libraries Government Documents Department

2008 Atomic and Molecular Interactions GRC-July 6-11, 2008

Description: The Atomic and Molecular Interactions Gordon Conferences is justifiably recognized for its broad scope, touching on areas ranging from fundamental gas phase and gas-condensed matter collision dynamics, to laser-molecule interactions, photophysics, and unimolecular decay processes. The meeting has traditionally involved scientists engaged in fundamental research in gas and condensed phases and those who apply these concepts to systems of practical chemical and physical interest. A key tradition in this meeting is the strong mixing of theory and experiment throughout. The program for 2008 conference continues these traditions. At the 2008 AMI GRC, there will be talks in 5 broadly defined and partially overlapping areas of intermolecular interactions and chemical dynamics: (1) Photoionization and Photoelectron Spectroscopy; (2) Molecules in Strong Fields; (3) Photodissociation Dynamics; (4) Astrochemistry; and (5) Reaction Dynamics. These areas encompass many of the most productive and exciting areas of chemical physics, including both reactive and nonreactive processes, intermolecular and intramolecular energy transfer, and photodissociation and unimolecular processes. Gas phase dynamics, van der Waals and cluster studies, laser-matter interactions and multiple potential energy surface phenomena will all be discussed. Limited funds are available to support attendance for students and post-docs. Advisors should email the conference chair requesting such support, and the students should apply online as usual.
Date: June 3, 2009
Creator: Gray, Arthur Suits Nancy Ryan
Partner: UNT Libraries Government Documents Department

Achieving the 30% Goal: Energy and Cost Savings Analysis of ASHRAE Standard 90.1-2010

Description: This Technical Support Document presents the energy and cost savings analysis that PNNL conducted to measure the potential energy savings of 90.1-2010 relative to 90.1-2004. PNNL conducted this analysis with inputs from many other contributors and source of information. In particular, guidance and direction was provided by the Simulation Working Group under the auspices of the SSPC90.1. This report documents the approach and methodologies that PNNL developed to evaluate the energy saving achieved from use of ASHRAE/IES Standard 90.1-2010. Specifically, this report provides PNNL’s Progress Indicator process and methodology, EnergyPlus simulation framework, prototype model descriptions. This report covers the combined upgrades from 90.1-2004 to 90.1-2010, resulting in a total of 153 addenda. PNNL has reviewed and considered all 153 addenda for quantitative analysis in the Progress Indicator process. 53 of those are included in the quantitative analysis. This report provides information on the categorization of all of the addenda, a summary of the content, and deeper explanation of the impact and modeling of 53 identified addenda with quantitative savings.
Date: May 24, 2011
Creator: Thornton, Brian A.; Rosenberg, Michael I.; Richman, Eric E.; Wang, Weimin; Xie, YuLong; Zhang, Jian et al.
Partner: UNT Libraries Government Documents Department