Link to the University of Pittsburgh Homepage
Link to the University Library System Homepage Link to the Contact Us Form

Theory and Applications of Quantum Monte Carlo

Deible, Michael (2015) Theory and Applications of Quantum Monte Carlo. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

PDF (Thesis_MDeible)
Updated Version

Download (1MB)


With the development of peta-scale computers and exa-scale only a few years away, the quantum Monte Carlo (QMC) method, with favorable scaling and inherent parrallelizability, is poised to increase its impact on the electronic structure community. The most widely used variation of QMC is the diffusion Monte Carlo (DMC) method. The accuracy of the DMC method is only limited by the trial wave function that it employs. The effect of the trial wave function is studied here by initially developing correlation-consistent Gaussian basis sets for use in DMC calculations. These basis sets give a low variance in variance Monte Carlo calculations and improved convergence in DMC. The orbital type used in the trial wave function is then investigated, and it is shown that Brueckner orbitals result in a DMC energy comparable to a DMC energy with orbitals from density functional theory and significantly lower than orbitals from Hartree-Fock theory. Three large weakly interacting systems are then studied; a water-16 isomer, a methane clathrate, and a carbon dioxide clathrate. The DMC method is seen to be in good agreement with MP2 calculations and provides reliable benchmarks. Several strongly correlated systems are then studied. An H4 model system that allows for a fine tuning of the multi-configurational character of the wave function shows when the accuracy of the DMC method with a single Slater-determinant trial function begins to deviate from multi-reference benchmarks. The weakly interacting face-to-face ethylene dimer is studied with and without a rotation around the π bond, which is used to increase the multi-configurational nature of the wave function. This test shows that the effect of a multi-configurational wave function in weakly interacting systems causes DMC with a single Slater-determinant to be unable to achieve sub-chemical accuracy. The beryllium dimer is studied, and it is shown that a very large determinant expansion is required for DMC to predict a binding energy that is in close agreement with experiment. Finally, water interacting with increasingly large acenes is studied, as is the benzene and anthracene dimer. Deviations from benchmarks are discussed.


Social Networking:
Share |


Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Deible, Michaelmjd87@pitt.eduMJD87
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee MemberLambrect, Danrielqclab@pitt.eduQCLAB
Committee MemberStar, Alexanderastar@pitt.eduASTAR
Committee MemberKeith, Johnjakeith@pitt.eduJAKEITH
Committee ChairJordan, Kennethjordan@pitt.eduJORDAN
Date: 14 September 2015
Date Type: Publication
Defense Date: 29 May 2015
Approval Date: 14 September 2015
Submission Date: 22 July 2015
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Number of Pages: 171
Institution: University of Pittsburgh
Schools and Programs: Dietrich School of Arts and Sciences > Chemistry
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: Quantum Monte Carlo
Date Deposited: 14 Sep 2015 14:31
Last Modified: 15 Nov 2016 14:29


Monthly Views for the past 3 years

Plum Analytics

Actions (login required)

View Item View Item