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Embedded correlated wavefunction description of local features within a crystalline environment.

機(jī)譯：晶體環(huán)境中局部特征的嵌入式相關(guān)波函數(shù)描述。

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This dissertation involves development, testing, and application of an embedded correlated wavefunction (ECW) theory, which has been in development in the Carter group for over a decade. Electronic structure methods are valuable tools for predicting properties of molecules and materials. In this work, we aim to accurately model local features in crystals for which a mean field description such as density functional theory (DFT) does not capture the physics of either the feature and/or the phenomenon. Although DFT has proven to be rather accurate for describing many materials, situations exist where it fails to provide even a qualitatively correct picture, e.g., strong electron-electron correlations, excited states, and open-shell systems. In the ECW theory, the total system is partitioned into a cluster of atoms containing the feature of interest, treated with CW theory, and a periodically infinite background region, treated with DFT. The effect of the background on the cluster is represented by an embedding potential derived from orbital-free DFT. With a pseudopotential-based version of the ECW theory, we study the adsorption of carbon monoxide (CO) on Cu(111) and Pt(111), well-known systems where standard DFT fails to predict the correct binding site preference and overbinds CO to the surface. The ECW predictions for the binding site preference are consistent with experimental finding for CO on both surfaces. Predicted binding energies for CO on Cu(111) are in excellent agreement with experiment, in contrast to DFT and non-embedded CW theory. We then develop a new all-electron implementation of the ECW method and apply it to the study of cobalt (Co) adatoms on coinage metal surfaces, systems that display the surface Kondo effect. Here, the spin of a magnetic impurity within a metal antiferromagnetically couples to the conduction electrons, creating a resonant state and producing anomalous low temperature behavior. This type of interaction arises from strong correlation effects that cannot be properly described by a mean field theory. The ECW predicted Co d-electronic structure, combined with earlier predictions for Co on Cu surfaces, provides an explanation of trends in tunneling behavior observed with scanning tunneling spectroscopy. Finally, we examine excited state energetics within bulk magnesium oxide as predicted with the all-electron ECW method and embedded CW methods that employ a classical description of the background crystal, in order to determine the best approach for the description of excited states within metal-oxide crystals. Preliminary results indicate that both CW treatment and embedding are necessary to describe the ionic crystal accurately, and that a classical point charge description of the background is superior to a DFT-based embedding potential. We also discuss some extensions of the ECW method that were considered but not pursued.
機(jī)譯：本文涉及嵌入式相關(guān)波函數(shù)（ECW）理論的開發(fā)，測試和應(yīng)用，該理論已在卡特小組中發(fā)展了十多年。電子結(jié)構(gòu)方法是預(yù)測分子和材料特性的有價值的工具。在這項工作中，我們旨在精確地建模晶體的局部特征，對于這些局部特征，諸如密度泛函理論（DFT）之類的平均場描述無法捕獲特征和/或現(xiàn)象的物理性質(zhì)。盡管已證明DFT在描述許多材料方面相當(dāng)準(zhǔn)確，但仍存在無法提供定性正確的圖像的情況，例如強(qiáng)電子-電子相關(guān)性，激發(fā)態(tài)和開殼系統(tǒng)。在ECW理論中，整個系統(tǒng)被劃分為包含感興趣特征的原子簇（使用CW理論處理）和周期性無限背景區(qū)域（使用DFT處理）。背景對簇的影響由無軌道DFT產(chǎn)生的嵌入勢表示。使用基于偽勢的ECW理論，我們研究了一氧化碳（CO）在Cu（111）和Pt（111）上的吸附，這是眾所周知的系統(tǒng)，其中標(biāo)準(zhǔn)DFT無法預(yù)測正確的結(jié)合位點(diǎn)偏好并過度結(jié)合CO到表面。 ECW對結(jié)合位點(diǎn)偏好的預(yù)測與在兩個表面上對CO的實(shí)驗發(fā)現(xiàn)相一致。與DFT和非嵌入式CW理論相反，預(yù)測的CO在Cu（111）上的結(jié)合能與實(shí)驗非常吻合。然后，我們開發(fā)了ECW方法的新的全電子實(shí)現(xiàn)，并將其應(yīng)用于造幣金屬表面（顯示表面近藤效應(yīng)的系統(tǒng)）中鈷（Co）原子的研究。在此，金屬中的磁性雜質(zhì)的自旋反鐵磁耦合至導(dǎo)電電子，從而形成共振狀態(tài)并產(chǎn)生異常的低溫行為。這種類型的相互作用源于均值場論無法正確描述的強(qiáng)相關(guān)效應(yīng)。 ECW預(yù)測的Co d電子結(jié)構(gòu)，與先前對Cu表面上Co的預(yù)測相結(jié)合，提供了使用掃描隧道光譜法觀察到的隧道行為趨勢的解釋。最后，我們檢查了采用全電子ECW方法和采用經(jīng)典背景晶體描述的嵌入式CW方法預(yù)測的塊狀氧化鎂中的激發(fā)態(tài)能量，以便確定描述金屬中激發(fā)態(tài)的最佳方法。氧化物晶體。初步結(jié)果表明，CW處理和嵌入對于準(zhǔn)確描述離子晶體都是必需的，并且背景的經(jīng)典點(diǎn)電荷描述優(yōu)于基于DFT的嵌入勢。我們還討論了已考慮但未采用的ECW方法的一些擴(kuò)展。

著錄項

  • 作者

    Sharifzadeh, Sahar.;

  • 作者單位

    Princeton University.;

  • 授予單位 Princeton University.;
  • 學(xué)科 Physics Condensed Matter.;Engineering Materials Science.
  • 學(xué)位 Ph.D.
  • 年度 2009
  • 頁碼 236 p.
  • 總頁數(shù) 236
  • 原文格式 PDF
  • 正文語種 eng
  • 中圖分類 工程材料學(xué);
  • 關(guān)鍵詞

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