Development of fragment-based quantum mechanical methods and combined quantum mechanical and molecular mechanical methods
2014-08
Loading...
View/Download File
Persistent link to this item
Statistics
View StatisticsJournal Title
Journal ISSN
Volume Title
Title
Development of fragment-based quantum mechanical methods and combined quantum mechanical and molecular mechanical methods
Authors
Published Date
2014-08
Publisher
Type
Thesis or Dissertation
Abstract
This thesis is dedicated to develop fragment-based QM methods and QM/MM schemes: For the first part, the fragment-based explicit polarization (X-Pol) method has been extended in three aspects: I. the inclusion of exchange repulsion terms in the X-Pol model is examined by antisymmetrizing the X-Pol Hartree-product wave function; this yields X-Pol with full eXchange, called X-Pol-X; II. the original X-Pol method, where all fragments are treated using the same electronic structure theory, is extended to a multilevel representations, called multilevel X-Pol, in which different electronic structure methods are used to describe different fragments; III. a fragment-based variational many-body (VMB) expansion method is described to directly account for exchange repulsion, charge delocalization (charge transfer) and dispersion interactions in the X-Pol method. For the second part, a universal QM/MM scheme, the projected hybrid orbital (PHO) method, is proposed to handle the covalent boundary at QM/MM interface at ab initio level with arbitrary basis sets. As an extension to the generalized hybrid orbital (GHO) method in which hybrid orbitals are constructed using the valence orbitals on the boundary atom, the PHO method further represents the core and valence electrons with a secondary, minimal basis set by projecting the original (primary) basis set used in the QM system. The PHO method is then validated on several aspects: geometry optimization, charge population and proton-affinity calculation. Comparison with standard QM results shows that PHO is a robust and balanced QM/MM scheme that yields satisfactory structural, electronic, and energetic properties.
Keywords
Description
University of Minnesota Ph.D. dissertation. August 2014. Major: Chemical Physics Advisor: Prof. Jiali Gao. 1 computer file (PDF); xii, 185 pages.
Related to
Replaces
License
Collections
Series/Report Number
Funding information
Isbn identifier
Doi identifier
Previously Published Citation
Suggested citation
Wang, Yingjie. (2014). Development of fragment-based quantum mechanical methods and combined quantum mechanical and molecular mechanical methods. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/167668.
Content distributed via the University Digital Conservancy may be subject to additional license and use restrictions applied by the depositor. By using these files, users agree to the Terms of Use. Materials in the UDC may contain content that is disturbing and/or harmful. For more information, please see our statement on harmful content in digital repositories.