Database optimization algorithm for empirical potentials

Zhang, Pinchao

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https://hdl.handle.net/2142/90714 Copy

Description

Title

Database optimization algorithm for empirical potentials

Author(s)

Zhang, Pinchao

Issue Date

2016-03-01

Director of Research (if dissertation) or Advisor (if thesis)

Trinkle, Dallas R.

Doctoral Committee Chair(s)

Trinkle, Dallas R.

Committee Member(s)

• Bellon, Pascal
• Chen, Yuguo
• Ferguson, Andrew

Department of Study

Materials Science & Engineerng

Discipline

Materials Science & Engr

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• Empirical potential models
• Optimization algorithm
• Bayesian statistics
• Monte Carlo
• Genetic algorithm
• Titanium oxygen interaction

Abstract

The development for accurate and efficient empirical potential models requires years of efforts and is highly intuitional. This study provides an automated, quantitative algorithm to find the optimal empirical potential model for a pre-determined testing set of desired structure properties. We employ Bayesian sampling technique to estimate the errors for the structural property functions in the testing set. We provide the first analytical derivations of how modifications in the fitting database affect the testing set errors. A new binary modified embedded-atom method functional form is developed for Ti-O interactions where O is in the dilute limit. The optimal Ti-O potential are tested against a variety of structure properties to verify the transferability of the potential. We propose and optimize two types of objective functions which measures the transferability in the testing set. One aims to minimize the relative errors of different fitting databases for the testing set, and the other uses the logistic function in classification regression analysis to categorize the prediction errors in the testing set into good and bad ones. We develop a parallelized genetic algorithm to efficiently evaluate the objective function and perform global search for the optimal empirical potential model.

Graduation Semester

2016-05

Type of Resource

text

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http://hdl.handle.net/2142/90714

Copyright and License Information

Copyright 2016 Pinchao Zhang

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