Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 20 of 60 for “"potential energy surfaces"”.
-
Machine Learning Coupled Potential Energy Surfaces
Recent advancements in machine learning (ML) for potential energy surfaces (PESs) have yielded promising results, with much of the focus on isolated ground-state surfaces. Extending machine learning to coupled excited state surfaces introduces significant challenges, however, particularly in …
-
Characterizing water-metal interfaces and machine learning potential energy surfaces
… single water molecules on both Pt and graphite surfaces. We find that a covalent bond forms between the single water molecule and the platinum surface, but not between the single water molecule and the graphite surface. We also discuss the effects that defects and dopants in the graphite and …
-
Optimisation of Gaussian process regressions of molecular potential energy surfaces
… Moreover, for our particular interest of potential energy surface learning, one usually deals with sparsity in the training data given the high computational cost of ab initio electronic structure calculations. This sparsity creates instability in the models that a Bayesian approach to …
-
Application of quantum Monte Carlo methods to molecular potential energy surfaces
… computational methods have been used to generate potential energy surfaces, which can help us simulate and interpret how atoms or molecules behave during a chemical reaction. For accurate work, <i>ab initio</i> wavefunction methods have traditionally been used, which have some disadvantages. For …
-
Potential Energy Surfaces for Intermolecular Proton Transfers in Crystalline Aspirin: A Computational Study
… density functional theory were used to model the potential energy surface of intermolecular proton transfers in crystalline aspirin. Using these surfaces the importance of intermolecular interactions and excited states to the proton transfer were also explored. In addition, the ability of ab …
-
Novel techniques for cold/ultracold molecular collisions
… mechanics. Experimental developments of low energy collisions will challenge the theoretical description of molecular interactions, and aid in validating the accuracy of the calculated potential energy surfaces. Scattering studies involving two different configurations of the apparatus, …
-
Contribución al estudio teórico de la influencia del disolvente sobre transiciones electrónicas y estados excitados en disolución empleando el método ASEP/MD
… ASEP/MD method (Averaged Solvent Electrostatic Potential from Molecular Dynamics) was extended to the study of photochemical properties of systems in condesed phase. Methods to calculate free energy differences related with electronic transitions and crossing points between potential energy …
-
Structure and Dynamics of Van Der Waals Molecules From Microwave Spectroscopy
… concerning the structures and intramolecular potential energy surfaces of these complexes.
-
The structure of carbon dioxide adsorbed on a sodium chloride (001) surface
Two sets of parameters and potential energy surfaces for a single CO$\sb2$ molecule adsorbed on the (001) face of a uniform semi-infinite crystal of NaCl were developed and tested using the Steepest Descent method. When the CO$\sb2$ molecule attains the absolute minimum of the potential energy it …
-
Theoretical Studies on the ultrafast photodissociation of molecules
… processes is the often complex topology of the potential energy surfaces due to coupling between the nuclear and electron motion: termed vibronic coupling. A known feature in potential energy surfaces due to vibronic coupling is the conical intersection and these play a role in all three systems …
-
Characterization of ETBE + Cl and Isooctane + Cl Combustion Products using Synchrotron Photoionization
… were identified. Relevant reaction dynamics on potential energy surfaces were calculated, reaction enthalpies of each individual step were presented using the CBS-QB3 composite model, and reaction pathways were proposed.</p>
-
ELECTRONIC MATRIX ISOLATION SPECTROSCOPIC STUDIES OF METAL ATOM PHOTOCHEMISTRY
… dynamics of the adducts along ground and excited potential energy surfaces. The final design of this matrix isolation apparatus incorporated unique features that abbreviated data acquisition time and obviated several experimental problems that have plagued previous matrix isolation studies. The …
-
A study of vibrating-rotating motions of polyatomic molecules
… in both rectilinear and curvilinear coordinates, Potential energy surfaces were obtained from fitting either ab initio or experimental data points by a series expansion of convenient functions in the same coordinates as the kinetic energy operator. We have formulated the problem such that the …
-
Quantum mechanical study of molecular switches : electronic structure, kinetics and dynamical aspects
… An influence of external electric fields on the potential energy surfaces, was also studied. Further, by the type, number and positioning of various substituent groups, systematic changes on activation energies and rates for the thermal cis-to-trans isomerization can be enforced. The nature of …
-
Holomorphic Hartree-Fock Theory: Moving Beyond the Coulson-Fischer Point
… creating kinks and discontinuities in the energy. This thesis develops a new theory - holomorphic Hartree-Fock (h-HF) - to analytically extend HF states across all molecular structures. By removing the complex-conjugation of orbital coefficients from the conventional HF equations, h-HF …
-
The Role of Electrical Interactions in Hydrogen Bonding
… bonded complexes. Spectroscopic constants and potential energy surfaces are all issues that may be addressed by theoretical investigations. One recurring conclusion from the various studies has been the importance of electrical interactions in hydrogen bonding. A simple model that includes both …
-
Development Of New Algorithms For Exploring The Potential Energy Landscape Of Chemical Reactions
… either ab initio or density functional theory potential energy surfaces.</p> <p> The final two chapters of this thesis focus on the development of a new path optimization framework, the Variational Reaction Coordinate (VRC) method. This framework seeks to improve upon the “chain of states” …
-
Measurement of the rate of hydrogen atom abstraction from methane and ethane by muonium
… in location of the transition states on the potential energy surfaces. Also, for the Mu variants, the reaction rates seem to be reduced less for vibrationally excited states of CH₄ and C₂H₆than for the ground states than is the case for the corresponding H atom reactions, an effect which …
Page 1 of 3