Utilizing Multireference Driven Similarity Renormalization Group to Study 3d Transition Metal Atoms and Hydrides Pubblico

Abstract

Transition metal complexes play a fundamental role in biological processes and

chemical catalysis; however, they remain difficult to study computationally. Computational

challenges arise due to the presence of strong and weak electron correlation and the

competition between states of different spin multiplicity. However, most computational

techniques do not adequately capture both forms of electron correlation. Most multireference

techniques accurately capture strong electron correlation while most single reference

techniques efficiently describe weak electron correlation. The primary difficulty, in studying 3d

transition metal compounds computationally is to capture both forms of electron correlation

within the calculation. Presented here is the utilization of the multireference driven similarity

renormalization group (MRDSRG) method to benchmark 3d transition metal hydrides. MRDSRG

can account for strong electron correlation through multiple Slater determinants and weak

electron correlation using a sliding parameter to control the extent the Hamiltonian is blockdiagonalized.

This thesis presents the analysis of several 3d transition metal hydrides, and the

first computation of the ionization energies of 3d transition metals with MRDSRG, with a

comparison to other computational techniques.

Table of Contents

1 Introduction………………………………………………………………………………….1

1.1) Introduction………………………………………………………………………………………1

1.2) The Schr.dinger Equation……………………………………………………………………..3

1.3) Full-Configuration Interaction………………………………………………………………….4

1.4) Hartree-Fock Theory and other Single-Reference Techniques……………………………7

1.5) Density Functional Theory……………………………………………………………………..8

1.6) Multireference Techniques…………………………………………………………………….9

a) Complete Active Space Self-Consistent Field Method…………………………………9

b) Atomic Valence Active Space……………………………………………………………10

c) Perturbative Multireference Driven Similarity Renormalization Group………………12

1.7) Electron Correlation……………………………………………………………………………14

2 Perturbative MRDSRG Calculations……………………………………………………17

2.1) Introduction……………………………………………………………………………………..17

2.2) Computational Methods……………………………………………………………………….18

2.3) First Ionization Energies………………………………………………………………………22

2.4) Analysis of the Flow Parameter………………………………………………………………25

2.5) Analysis of 3d Transition Metal Hydrides……………………………………………………28

3 Conclusion………………………………………………………………………………….34

About this Master's Thesis

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School	Laney Graduate School
Department	Chemistry
Degree	M.S.
Submission	Master's Thesis
Language	English
Research Field	Chemistry, Physical
Parola chiave	DSRG Transition metals MRDSRG
Committee Chair / Thesis Advisor	Francesco Evangelista, Emory University
Committee Members	Raphael Ribeiro, Emory University Joel Bowman, Emory University

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