Events Calendar

26 Feb
PhD Proposal Defense - Priyanka Bholanath Shukla
Event Type

Defenses

Topic

Research

Target Audience

Faculty, Graduate Students, Postdocs

University Unit
Department of Chemical and Petroleum Engineering
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PhD Proposal Defense - Priyanka Bholanath Shukla

This is a past event.

 

Title: Assessing Accuracy and Improving Efficiency of Self-Interaction Corrected Density Functional Theory

 

Abstract: Density functional theory, commonly used for predicting chemical properties, suffers from self-interaction errors, which may result in underprediction of reaction barriers and inaccurate descriptions of properties such as dissociation energy, charge transfer, and others. In this work, we employ the Fermi-Löwdin Self-Interaction Correction (FLOSIC) method to implement the Perdew-Zunger self-interaction correction (PZSIC) energy, which can only be implemented on an orbital-by-orbital basis. Our purpose is to assess the accuracy of reaction barrier heights for uncatalyzed and catalyzed chemical reactions. For uncatalyzed reactions, we analyze the results of PZSIC calculations on a per-orbital basis to understand how PZSIC corrects the underestimation of barrier heights. We found that orbitals directly involved in bond-breaking and bond-making events, which are typically stretched bond orbitals in transition states, make the largest contribution to the self-interaction corrections. We have studied the impact of PZSIC on several reactions involved in the selective catalytic reduction of NOx on a model of a zeolite catalyst, Cu-SSZ-13. We found that PZSIC improves barrier heights for several of the reactions. However, in some cases, it predicts small or negative barriers. We found that reactions involving a change in the oxidation state of the Cu atom in the model Cu-SSZ-13 cluster from Cu+ to Cu2+ give rise to very large errors in the PZSIC energies. We attributed these errors to an unphysical energy penalty for a filled or half-filled 3d shell in the PZSIC calculation. Calculations on other transition metals show similar energy penalties for Cr, Mn, Zn, Ga, and Ge when an electron is removed from a closed or half-filled 3d shell. We plan to further investigate the source of the SIC energy penalty and how to correct it in a PZSIC calculation. Our future work will focus on examining important chemical reaction barriers and adsorption energies, observing the SIC energy penalty across different single transitional metal atom catalysts. Additionally, our goal is to understand the behavior of the SIC energy penalty in reactions taking place on catalysts containing multiple transition metals within a system.

 

Chair:

J. Karl Johnson

Department of Chemical and Petroleum Engineering, University of Pittsburgh

 

Committee Members:

Dr. John A. Keith

Department of Chemical and Petroleum Engineering, University of Pittsburgh

 

Dr. Robert M. Enick

Department of Chemical and Petroleum Engineering, University of Pittsburgh

 

Dr. Kenneth D. Jordan

Department of Chemistry, University of Pittsburgh

 

Dr. Koblar Alan Jackson

Physics Department and Science of Advanced Materials Program, Central Michigan University

 

Dial-In Information

Zoom link: https://pitt.zoom.us/j/92169080203

Meeting ID: 921 6908 0203

Monday, February 26 at 11:00 a.m. to 1:00 p.m.

Benedum Hall, 1145
3700 O'Hara Street, Pittsburgh, PA 15261

PhD Proposal Defense - Priyanka Bholanath Shukla

 

Title: Assessing Accuracy and Improving Efficiency of Self-Interaction Corrected Density Functional Theory

 

Abstract: Density functional theory, commonly used for predicting chemical properties, suffers from self-interaction errors, which may result in underprediction of reaction barriers and inaccurate descriptions of properties such as dissociation energy, charge transfer, and others. In this work, we employ the Fermi-Löwdin Self-Interaction Correction (FLOSIC) method to implement the Perdew-Zunger self-interaction correction (PZSIC) energy, which can only be implemented on an orbital-by-orbital basis. Our purpose is to assess the accuracy of reaction barrier heights for uncatalyzed and catalyzed chemical reactions. For uncatalyzed reactions, we analyze the results of PZSIC calculations on a per-orbital basis to understand how PZSIC corrects the underestimation of barrier heights. We found that orbitals directly involved in bond-breaking and bond-making events, which are typically stretched bond orbitals in transition states, make the largest contribution to the self-interaction corrections. We have studied the impact of PZSIC on several reactions involved in the selective catalytic reduction of NOx on a model of a zeolite catalyst, Cu-SSZ-13. We found that PZSIC improves barrier heights for several of the reactions. However, in some cases, it predicts small or negative barriers. We found that reactions involving a change in the oxidation state of the Cu atom in the model Cu-SSZ-13 cluster from Cu+ to Cu2+ give rise to very large errors in the PZSIC energies. We attributed these errors to an unphysical energy penalty for a filled or half-filled 3d shell in the PZSIC calculation. Calculations on other transition metals show similar energy penalties for Cr, Mn, Zn, Ga, and Ge when an electron is removed from a closed or half-filled 3d shell. We plan to further investigate the source of the SIC energy penalty and how to correct it in a PZSIC calculation. Our future work will focus on examining important chemical reaction barriers and adsorption energies, observing the SIC energy penalty across different single transitional metal atom catalysts. Additionally, our goal is to understand the behavior of the SIC energy penalty in reactions taking place on catalysts containing multiple transition metals within a system.

 

Chair:

J. Karl Johnson

Department of Chemical and Petroleum Engineering, University of Pittsburgh

 

Committee Members:

Dr. John A. Keith

Department of Chemical and Petroleum Engineering, University of Pittsburgh

 

Dr. Robert M. Enick

Department of Chemical and Petroleum Engineering, University of Pittsburgh

 

Dr. Kenneth D. Jordan

Department of Chemistry, University of Pittsburgh

 

Dr. Koblar Alan Jackson

Physics Department and Science of Advanced Materials Program, Central Michigan University

 

Dial-In Information

Zoom link: https://pitt.zoom.us/j/92169080203

Meeting ID: 921 6908 0203

Monday, February 26 at 11:00 a.m. to 1:00 p.m.

Benedum Hall, 1145
3700 O'Hara Street, Pittsburgh, PA 15261

Event Type

Defenses

Topic

Research

Target Audience

Faculty, Graduate Students, Postdocs

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