The thermodynamics of three-dimensional, single-component elastic crystalline solids was developed by Slattery and Lagoudas (2005). Considering the in¯nitesimal deformations, the stress can be expressed as a function of the lattice vectors and density in the reference configuration and ¹(I;mn), which is defined as the derivative of specific Helmoholtz free energy with respect to the I(mn). Using the Cauchy - Born rule to connect the interatomic potential energy and the specific Helmholtz free energy, it is possible to calculate the elastic properties of both nano-scale materials such as carbon nanotubes and macro-scale materials such as diamond and silicon. In this study, we used Terso® (1988a) - Brenner (1990b) Potential, Terso® (1988b) potential and Finnis and Sinclair (1984) potential for carbon, silicon, and vanadium systems respectively. Using the interatomic potentials to describe the specific Helmholtz free energy, the elastic properties of graphite, diamond, silicon and vanadium were calculated. This method was also extended to the calculation of Young's modulus of single-walled carbon nanotubes (SWCNTs), which are composed of a two dimensional array of carbon atoms. For SWCNT, we get good agreement with the available experimental data. For diamond and silicon, C11 and C12 were consistent with both the superelastic model and the experimental data. The difference of C44 between the calculation and experimental data was due to accuracy of the potential functions.

This dissertation provides one methodology to determine potential energy savings of buildings with limited information. This methodology is based upon the simplified energy analysis procedure of HVAC systems and the control of the comfort conditions. Numerically, the algorithm is a tailored exhaustive search over all the independent variables that are commonly controlled for a specific type of HVAC system. The potential energy savings methodology has been applied in several buildings that have been retrofitted and/or commissioned previously. Results from the determined savings for the Zachry building at Texas A&M after being commissioned show a close agreement to the calculated potential energy savings (about 85%). Differences are mainly attributed to the use of simplified models. Due to the restriction of limited information about the building characteristics and operational control, the potential energy savings method requires the determination of parameters that characterize its thermal performance. Thus, a calibrated building is needed. A general procedure has been developed to carry out automated calibration of building energy use simulations. The methodology has been tested successfully on building simulations based on the simplified energy analysis procedure. The automated calibration is the minimization of the RMSE of the energy use over daily conditions. The minimization procedure is fulfilled with a non-canonical optimization algorithm, the Simulated Annealing, which mimics the Statistical Thermodynamic performance of the annealing process. That is to say, starting at a specified temperature the algorithm searches variable-space states that are steadier, while heuristically, by the Boltzmann distribution, the local minima is avoided. The process is repeated at a new lower temperature that is determined by a specific schedule until the global minimum is found. This methodology was applied to the most common air-handler units producing excellent results for ideal cases or for samples modified with a 1% white noise.

The vibrational potential energy surfaces in electronic ground and excited states of several ring molecules were investigated using several different spectroscopic methods, including far-infrared (IR), Raman, ultraviolet (UV) absorption, fluorescence excitation (FES), and single vibronic level fluorescence (SVLF) spectroscopies. Based on new information obtained from SVLF and millimeter wave spectra, the far-IR spectra of coumaran were reassigned and the one-dimensional ring-puckering potential energy functions for several vibrational states in the S0 ground state were determined. The barrier was found to be 154 cm-1 and the puckering angles to be ± 25°, in good agreement with the millimeter wave barrier of 152 cm-1 and puckering angles of ± 23°. Moreover, the UV absorption and FES spectra of coumaran allowed the one-dimensional ring-puckering potential energy functions in the S1 excited state to be determined. The puckering barrier is 34 cm-1 for the excited state and the puckering angles are ± 14°. Several calculations with different basis sets have been carried out to better understand the unusual vibrational frequencies of cyclopropenone. It was shown that there is strong interaction between the C=O and symmetric C-C stretching vibrations. These results differ quantitatively from a previous normal coordinate calculation and interpretation. The vapor-phase Raman spectrum of 3,7-dioxabicyclo[3.3.0]oct-1,5-ene was analyzed and compared to the predicted spectrum from DFT calculations. The spectrum further shows it has D2h symmetry, in which the skeletons of both rings are planar. The infrared and Raman spectra of vapor-phase and liquid-phase 1,4-benzodioxan and 1,2,3,4-tetrahydronaphthalene were collected and the complete vibrational assignments for both molecules were made. Theoretical calculations predicted the barriers to planarity to be 4809 cm-1 for 1,2,3,4-tetrahydonaphthalene and 4095 cm-1 for 1,4-benzodioxan. The UV absorption, FES, and SVLF spectra of both molecules were recorded and assigned. Both one and two-dimensional potential energy functions of 1,4-benzodioxan for the ring-twisting and ring-bending vibrations were carried out for the S0 and S1(π,π*) states, and these were consistent with the high barriers calculated for both states. The low-frequency spectra of 1,2,3,4-tetrahydronaphthalene in both S0 and S1(π,π*) states were also analyzed.

Thesis (Ph. D.)--University of Washington, 2001. / Vita. Includes bibliographical references (p. 129-136).

This thesis has improved Baltazar's methodology for potential energy savings estimation from retro-commissioning/retrofits measures. Important improvements and discussions are made on optimization parameters, limits on optimization parameter values, minimum airflow setting for VAV systems, space load calculation, simulation of buildings with more than one type of system, AHU shutdown simulation, and air-side simulation models. A prototype computer tool called the Potential Energy Savings Estimation (PESE) Toolkit is developed to implement the improved methodology and used for testing. The implemented methodology is tested in two retro-commissioned on-campus buildings with hourly measured consumption data. In the Sanders Corps of Cadets Center, the optimized profiles of parameter settings in single parameter optimizations can be explained with engineering principles. It reveals that the improved methodology is implemented correctly in the tool. The case study on the Coke Building shows that the improved methodology can be used in buildings with more than one system type. The methodology is then used to estimate annual potential energy cost savings for 14 office buildings in Austin, TX with very limited information and utility bills. The methodology has predicted an average total potential savings of 36% for SDVAV systems with electric terminal reheat, 22% for SDVAV systems with hot water reheat, and 25% for DDVAV systems. The estimations are compared with savings predicted in the Continuous Commissioning assessment report. The results show it may be helpful to study the correlation by using generalized factors of assessment predicted energy cost savings to estimated potential energy cost savings. The factors identified in this application are 0.68, 0.66, and 0.61 for each type of system. It is noted that one should be cautious in quoting these factors in future projects. In the future, it would be valuable to study the correlation between measured savings and estimated potential savings in a large number of buildings with retrocommissioning measures implemented. Additionally, further testing and modifications on the PESE Toolkit are necessary to make it a reliable software tool.

Mechanochemistry, the use of mechanical stress to activate chemical reactions, has emerged as a significant area of interest in recent years. Two theoretical approaches have been developed to simulate mechanochemical processes: COnstrained Geometries Simulate External Force (COGEF) and External Force is Explicitly Included (EFEI). In the COGEF method, mechanical stress is simulated by increasing the distance between atoms in a molecule that serve as pulling points (PPs) at a constant rate. In the EFEI methods, a constant external force (Fext) is applied between PPs, allowing the atoms to move to maintain that force. Both methods have been used in the literature to study the ring opening of cyclobutene under mechanochemical conditions. These studies have shown that applying a force between cis PPs in cyclobutene induces ring opening along the conrotatory pathway in COGEF-based simulations and ring opening along the disrotatory pathway in EFEI-based simulations. The latter is consistent with experiments. The work in this thesis identifies the origin of the differences in the outcomes obtained with these two methods, which may be of interest in the context of researchers selecting methods to simulate mechanochemical processes. The results demonstrate that the origin of the difference in behaviour is related to the manner in which these methods alter the potential energy surface (PES) through the application of a mechanical stress. Specifically, the PES obtained with the COGEF method does not contain a minimum energy pathway (MEP) linking cyclobutene to the disrotatory product, whereas the EFEI surface does contain such a path. The differences in PESs suggest that the EFEI method is more suitable to simulate mechanochemical processes. The EFEI approach was then used to examine how the electronic structure evolves to permit a formally forbidden disrotatory reaction to occur. The circumvention of the Woodward-Hoffmann rules was not due to a change in the electronic structure. Instead, the application of an external force shifts the transition state along the reaction coordinate towards the reactants, lowering the barrier for the reactions. The orbital effects that disfavor movement from reactants to products are rendered secondary to mechanochemical factors. / Thesis (Master, Chemistry) -- Queen's University, 2011-12-14 16:47:24.197

A new intermolecular potential energy surface, rovibrational transition frequencies, and line strengths are computed for OCS-OCS and CO2-CS2. The potentials were made by fitting energies obtained from explicitly correlated coupled-cluster calculations and fit using an interpolating moving least squares method. Rovibrational transition frequencies are also calculated for four isotopologues of the N2O dimer using a previously presented potential energy surface. The rovibrational Schroedinger equation for all three dimers is solved with a symmetry-adapted Lanczos algorithm and an uncoupled product basis set. All four intermolecular coordinates are included in the calculation. On the OCS-OCS potential energy surface, a previously unknown, cross-shaped isomer is found along with polar and non-polar isomers. For CO2-CS2, the previously found cross-shaped minima is found along with a slipped-parallel configuration. The associated wavefunctions and energy levels for each of these isomers is presented. To identify states that have a permanent dipole, both calculations of line strengths and vibrational parent analysis is used. For non polar states of, OCS-OCS, and N2O-N2O isotopologues, and all CO2-CO2 states, only vibrational parent analysis was used. Calculated rotational constants differ from their experimental counterparts by less than 0.001 wavenumbers for OCS-OCS and CO2-CS2, and less than 0.002 wavenumbers for any N2O-N2O isotopologue. / Thesis (Master, Physics, Engineering Physics and Astronomy) -- Queen's University, 2012-08-23 13:19:45.294

The infrared, Raman and ultraviolet spectra of pyridine-d0 and pyridine-d5 were recorded and assigned with a focus on the low-frequency vibrational modes in the S1(n,pi*) electronic excited state. An energy map for the low-frequency modes was constructed and the data for the v18 mode allowed a highly anharmonic one-dimensional potential energy function to be determined for the S1 excited state. In this S1(n,pi*) state, pyridine is quasi-planar and very floppy with a barrier to planarity of 3 cm^-1. The infrared, Raman and ultraviolet spectra of 2-fluoropyridine (2FPy) and 3-fluoropyridine (3FPy) have been collected and assigned. For 2FPy about 150 bands were observed for the transitions to the vibronic levels of the S(pi, pi*) state at 38,030.4 cm^-1. For 3FPy more than a hundred absorption bands associated with the S(n,pi*) state at 35,051.7 cm^-1 and about forty broad bands associated with the S(pi, pi*) state at 37,339 cm^-1 were observed. The experimental work was complemented by ab initio calculations and these also provided calculated structures for 2FPy, 3FPy, and pyridine. They showed that the fluorine atom on the ring participates in the pi bonding. The gas-phase Raman spectra of 1,3-butadiene and its 2,3-d2, 1,1,4,4-d4, and d6 isotopomers have been recorded with high sensitivity in the region below 350 cm-1, in order to investigate the internal rotation (torsional) vibration. The data for all the isotopomers were then fit using a one-dimensional potential energy function of the form V = (1/2)Sigma(Vn(1-cos (phi))). The energy difference between trans and gauche forms was determined to be about 1030 cm^-1 (2.94 kcal/mol), and the barrier between the two equivalent gauche forms to be about 180 cm^-1 (0.51 kcal/mol), which agrees well with high-level ab initio calculations. The results from an alternative set of assignments also fits the data quite well are also presented. Combination and hot band series involving the v13 torsional vibration of the trans rotamer were observed for each of the butadiene isotopomers. In addition, the high signal to noise of the Raman spectra made it possible to detect several dozen bands of the gauche rotor which makes up only about 2% of the molecules at ambient temperature.

No description available.

The Morse/Long Range (MLR) potential has become one of the most reliable and highly used potential energy functions for diatomic molecules. It includes the theoretical long range behaviour that diatomic molecules are known to exhibit as they approach the dissociation limit. Heavy alkali metals with adjacent electronic states often exhibit strong coupling between the spin and orbital angular momentum. The ground state X¹Σg⁺ and the lowest lying triplet state aᶟΣᵤ⁺ of Cs₂ exhibit such coupling effects and as a result, modeling the highest vibrational states of these states is a non-trivial problem. Utilizing scattering length values obtained from published analysis of 60 Feshbach resonances, the correct form of the potential energy function was determined. Moreover, the scattering length values were used to determine the correct leading dispersion coefficient that describes the true form of the long-range potential energy functions. All previous attempts to determine global potential energy functions for these states have considered only the optical spectroscopic data. This is the first ever effort attempting to use scattering lengths determined from cold atom collision experiments in a combined analysis with conventional spectroscopic data.