Buxton, Samuel (2019) Development and application of path integral methods to study nuclear quantum effects in aqueous systems. PhD thesis, University of Warwick.

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Abstract

Nuclear quantum effects have been shown to play a large role in defining the properties of chemical systems. However including these in computational simulations for example using path integral methods is far more computationally expensive than a classical simulation where these effects are ignored. This is because the number of individual force calculations is greatly increased when using a path integral method. This means that for some systems and system sizes it is difficult to computationally evaluate fully quantum properties. To address this, methods have been developed that can accelerate this simulations with minimal loss of accuracy, however the most popular methods all suffer from drawbacks which limits their application to certain types of system. This work presents a novel method for increasing the speed of path integral simulations that employs Kernel-Ridge Regression to enable fewer individual force calculations during the simulation while maintaining accuracy. The main advantage of this method lies in its ability to be applied to any system of interest with no conditions or prior assumptions about the potential energy surface. Results for this method are very positive when applied to two systems where quantum effects are prevalent, liquid water and para-hydrogen. In addition to this work, an investigation is carried out into the role of nuclear quantum effects in the free energies of hexagonal and cubic ice, as hexagonal is only more stable by _ 40 J mol

Item Type:	Thesis or Dissertation (PhD)
Subjects:	Q Science > QC Physics Q Science > QD Chemistry
Library of Congress Subject Headings (LCSH):	Quantum theory, Nuclear physics, Path integrals, Water -- Surfaces, Potential energy surfaces
Official Date:	July 2019
Dates:	Date Event July 2019 UNSPECIFIED
Institution:	University of Warwick
Theses Department:	Department of Chemistry
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Habershon, Scott
Sponsors:	Engineering and Physical Sciences Research Council
Format of File:	pdf
Extent:	xv, 167 leaves : illustrations, charts
Language:	eng

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