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4f: The Quantum Levels /

Record Type:	Electronic resources : Monograph/item
Title/Author:	4f: The Quantum Levels // Andres Garcia Alejo.
Author:	Garcia Alejo, Andres,
Description:	1 electronic resource (98 pages)
Notes:	Source: Dissertations Abstracts International, Volume: 85-12, Section: B.
Contained By:	Dissertations Abstracts International85-12B.
Subject:	Physical chemistry. -
Online resource:	https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=31239167
ISBN:	9798382802015

4f: The Quantum Levels /
Garcia Alejo, Andres,

4f: The Quantum Levels /Andres Garcia Alejo. - 1 electronic resource (98 pages)

Source: Dissertations Abstracts International, Volume: 85-12, Section: B.

The focus of this thesis is the study of lanthanide-based molecules using three different levels of theory. The first chapter is the introduction and background for the rest of the thesis. In the introductory chapter, the importance of studying lanthanides and their applications on different fields such as material sciences, biological systems and others is presented. It also includes information describing the 3 levels of theory used: Density Functional Theory (DFT), Complete Active Space Self Consistent Field (CASSCF)and Variational Quantum Eigensolver (VQE).The first chapter of the thesis describes the work done using DFT. That study shows the development of a new computational framework to compute relative binding strength between organic ligands and a lanthanum central atom. This work shows a strong correlation (R2=0.89) between the computed and experimental binding constants. The most important part of the method used was the inclusion of an implicit solvent model, adding some of the contribution of solvent effects without adding an additional number of atoms to the simulation.The second chapter is the first one out of two in the CASSCF level of theory. This part of the thesis shows the collaboration with experimental groups at Ames National Laboratory who synthesized and measured magnetic properties of new dysprosium and erbium centered complexes using silyl ligands. My work in this collaboration is the computational prediction of magnetic properties of the newly synthesized complexes. The experimental measurements of erbium compounds were verified to agree closely with the theory. For dysprosium, it was discovered that the multiple spatial configurations of the complex in the crystal caused significant quenching of the material's magnetization. When performing dilusions of Dy in the crystal, the measured magnetic properties start converging towards the theoretical values. This result indicates that the multiple configurations of the complexes were the reason for the quenching.The third chapter is a computational study expanding on the work from chapter 3 focusing on the dysprosium complexes. While calculating magnetic properties of the complexes, the ground state crystal field energy manifolds of the molecules were also computed. Two main questions are addressed in the computational study. The first property of interest is that of the presence of a nearby phenyl ring, which changes the splitting pattern of the first four energy levels of the manifold. The second idea of interest is discovering how replacing the nearest hydrogen atom for a more electronegative halogen atom would impact the energy level spacing of the ground state energy manifold. The results reveal a trend where the addition of the halogen atom interacting with the Dy center changed the overall height of the energy level manifold. Being able to tune the energy level manifold of these types of compounds is useful because molecules with specifically designed properties can be made if it is understood how to properly tune the energy level spacing and pattern.The fourth chapter shows a collaborative study with Berkeley National Laboratory where cerium dioxide is studied using a quantum computer simulator. This is the first attempt at using quantum computers to study the active space of a lanthanide molecule. The approach used for this study is combining a classical quantum chemistry calculation for the electrons outside of the active space and using an ideal quantum VQE simulation to compute the active space with higher accuracy. In addition to that, the recently developed derandomized classical shadow approximation is used to reduce the number of circuits needed for the simulation and make it feasible in a reasonable timeframe.Finally, the conclusion of the thesis compiles the important ideas and discoveries for my doctoral work. It reiterates once again the importance of studying lanthanides, since they currently have important applications and have much more waiting to be discovered. Finally, it concludes that a broad number of computational methods prove useful in the study of the 4f block of elements depending on what property needs to be studied and the computational and time resources available.

English

ISBN: 9798382802015Subjects--Topical Terms:

1981412
Physical chemistry.
Subjects--Index Terms:

Complete Active Space Self Consistent Field

4f: The Quantum Levels /
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500 $a Source: Dissertations Abstracts International, Volume: 85-12, Section: B.
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520 $a The focus of this thesis is the study of lanthanide-based molecules using three different levels of theory. The first chapter is the introduction and background for the rest of the thesis. In the introductory chapter, the importance of studying lanthanides and their applications on different fields such as material sciences, biological systems and others is presented. It also includes information describing the 3 levels of theory used: Density Functional Theory (DFT), Complete Active Space Self Consistent Field (CASSCF)and Variational Quantum Eigensolver (VQE).The first chapter of the thesis describes the work done using DFT. That study shows the development of a new computational framework to compute relative binding strength between organic ligands and a lanthanum central atom. This work shows a strong correlation (R2=0.89) between the computed and experimental binding constants. The most important part of the method used was the inclusion of an implicit solvent model, adding some of the contribution of solvent effects without adding an additional number of atoms to the simulation.The second chapter is the first one out of two in the CASSCF level of theory. This part of the thesis shows the collaboration with experimental groups at Ames National Laboratory who synthesized and measured magnetic properties of new dysprosium and erbium centered complexes using silyl ligands. My work in this collaboration is the computational prediction of magnetic properties of the newly synthesized complexes. The experimental measurements of erbium compounds were verified to agree closely with the theory. For dysprosium, it was discovered that the multiple spatial configurations of the complex in the crystal caused significant quenching of the material's magnetization. When performing dilusions of Dy in the crystal, the measured magnetic properties start converging towards the theoretical values. This result indicates that the multiple configurations of the complexes were the reason for the quenching.The third chapter is a computational study expanding on the work from chapter 3 focusing on the dysprosium complexes. While calculating magnetic properties of the complexes, the ground state crystal field energy manifolds of the molecules were also computed. Two main questions are addressed in the computational study. The first property of interest is that of the presence of a nearby phenyl ring, which changes the splitting pattern of the first four energy levels of the manifold. The second idea of interest is discovering how replacing the nearest hydrogen atom for a more electronegative halogen atom would impact the energy level spacing of the ground state energy manifold. The results reveal a trend where the addition of the halogen atom interacting with the Dy center changed the overall height of the energy level manifold. Being able to tune the energy level manifold of these types of compounds is useful because molecules with specifically designed properties can be made if it is understood how to properly tune the energy level spacing and pattern.The fourth chapter shows a collaborative study with Berkeley National Laboratory where cerium dioxide is studied using a quantum computer simulator. This is the first attempt at using quantum computers to study the active space of a lanthanide molecule. The approach used for this study is combining a classical quantum chemistry calculation for the electrons outside of the active space and using an ideal quantum VQE simulation to compute the active space with higher accuracy. In addition to that, the recently developed derandomized classical shadow approximation is used to reduce the number of circuits needed for the simulation and make it feasible in a reasonable timeframe.Finally, the conclusion of the thesis compiles the important ideas and discoveries for my doctoral work. It reiterates once again the importance of studying lanthanides, since they currently have important applications and have much more waiting to be discovered. Finally, it concludes that a broad number of computational methods prove useful in the study of the 4f block of elements depending on what property needs to be studied and the computational and time resources available.
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653 $a Density Functional Theory
653 $a Lanthanides
653 $a Quantum computing
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710 2 $a Iowa State University. $b Chemistry. $e degree granting institution. $3 3817124
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