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  4. TOWARDS MORE ACCURATE AND EFFICIENT QUANTUM MONTE CARLO CALCULATIONS: TWO IMPROVEMENTS

TOWARDS MORE ACCURATE AND EFFICIENT QUANTUM MONTE CARLO CALCULATIONS: TWO IMPROVEMENTS

File(s)
Han_cornell_0058O_10151.pdf (687.34 KB)
Permanent Link(s)
https://doi.org/10.7298/X4R78CBK
https://hdl.handle.net/1813/56863
Collections
Cornell Theses and Dissertations
Author
Han, Mingtong
Abstract

A pair-product projector, which projects onto an intrinsically Fermionic ground state, is implemented as part of a newly proposed Projection Monte Carlo method aimed at overcoming the Fermionic Sign Problem without employing the Fixed-Node approximation. Evaluating the fully anti-symmetrized pair- product projector requires factorial time. Three polynomial-time approximations are implemented and shown to be very close to the fully anti-symmetrized projector. A Fortran program is developed to generate configuration state functions for atomic systems using the projection method, with the goal of building all symmetries of a system into the trial wave functions used in Quantum Monte Carlo calculations. This brings an additional advantage of a significantly reduced number of variational parameters in trial wave functions. The program makes use of a bit-packed representation of Slater determinants and various algorithms to cut down run time and memory cost.

Date Issued
2017-08-30
Keywords
Physics
•
CSF
•
Pair-product Projector
•
Projection Monte Carlo
•
QMC
•
Trial wavefunctions
Committee Chair
Muller, David Anthony
Committee Member
Tardos, Eva
Umrigar, Cyrus Jehangir
Degree Discipline
Applied Physics
Degree Name
M.S., Applied Physics
Degree Level
Master of Science
Type
dissertation or thesis

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