Zhang Liang = 乙烯溴在異丁基杯(四)芳烴晶體中擴散機理的從頭算研究 / 章良. / Thesis submitted in: August 2004. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references. / Text in English; abstracts in English and Chinese. / Zhang Liang = Yi xi xiu zai yi ding ji bei (si) fang jing jing ti zhong kuo san ji li de cong tou suan yan jiu / Zhang Liang. / TITLE PAGE --- p.i / THESIS COMMUTE --- p.ii / ABSTRACT (English) --- p.iii / ABSTRACT (Chinese) --- p.iv / ACKNOWLEDGMENTS --- p.v / TABLE OF CONTENTS --- p.vi / LIST OF FIGURES --- p.viii / LIST OF TABLES --- p.ix / Chapter CHAPTER 1 --- Introduction / Chapter 1.1 --- Background Information of Calixarenes --- p.1 / Chapter 1.1.1 --- "History, Synthesis and Applications" --- p.1 / Chapter 1.1.2 --- Physical Properties --- p.2 / Chapter 1.1.3 --- Conformation of Calix[4]arenes --- p.3 / Chapter 1.1.4 --- Inclusion and Host-Guest Interactions --- p.4 / Chapter 1.2 --- Computational Theory --- p.8 / Chapter 1.2.1 --- Framework of Self-Consistent Field (SCF) --- p.8 / Chapter 1.2.2 --- Density function theory (DFT) --- p.9 / Chapter 1.3 --- Constrained Optimization Methods --- p.13 / Chapter 1.3.1 --- Introduction --- p.13 / Chapter 1.3.2 --- Augmented Lagrangian Method --- p.14 / Chapter 1.4 --- References --- p.16 / Chapter CHAPTER 2 --- Transformations of TBC4 Crystals / Chapter 2.1 --- Introduction and Experimental Results --- p.19 / Chapter 2.2 --- "II (""ab/ab"") to I (""ab/cd"") Transformation" --- p.21 / Chapter 2.3 --- "I (""ab/cd"") to III (Capsule) Transformation" --- p.25 / Chapter 2.4 --- Torsion of Capsulation --- p.27 / Chapter 2.5 --- References --- p.31 / Chapter CHAPTER 3 --- Diffusion through TBC4 Crystal / Chapter 3.1 --- Experimental Facts --- p.32 / Chapter 3.1.1 --- Kinds of TBC4 Inclusions --- p.32 / Chapter 3.1.2 --- "Inclusions of O2, vinyl bromide, toluene in TBC4" --- p.36 / Chapter 3.2 --- Diffusion of 02 in “ab/cd´ح TBC4 --- p.40 / Chapter 3.3 --- Diffusion of Vinyl Bromide through TBC4 --- p.44 / Chapter 3.3.1 --- "Vinyl bromide diffuses in ""ab/cd"" TBC4" --- p.45 / Chapter 3.3.2 --- Transformation/migration mechanism --- p.47 / Chapter 3.4 --- References --- p.51

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Title from PDF of title page (University of Missouri--Columbia, viewed on Feb 24, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Dissertation advisor: Dr. Jerry L. Atwood. Vita. Includes bibliographical references.

Thesis (Ph. D.), Memorial University of Newfoundland, 1998. / Bibliography: leaves 112-121.

Yes / Tailoring the physical properties of molecular crystals though the construction of solid solutions requires the existence of isostructural crystals. Simple substitutions of a given molecular framework can give a range of different crystal structures. A set of quinoxaline derivatives, C8H4N2(C6H4X)2,Q3,3′X2, has been investigated (X = F, Cl, Br, I and Me) where kinetic factors generated a set of isostructural crystals for the lighter halogens (F, Cl, Br) alone. Computational analysis shows that the stabilising interactions are maximal for Cl, while DSC studies demonstrate the existence of more stable polymorphs for both F and Br containing systems. Steric factors appear to have a lower contribution than the balance of weaker hydrogen and halogen bonding shown by the Me and I containing systems displaying different packing driven by CH⋯N/CH⋯π bonds and I⋯I bonds respectively.

The thesis entitled “Addressing subtle physicochemical features exhibited by molecular crystals via Experimental and Theoretical Charge Density Analysis” consists of five chapters. An introductory note provides a brief description of experimental and theoretical charge density methodology, followed by its utilization in obtaining certain physical and chemical properties in molecular crystals. Chapter 1 addresses not so easily accessed molecular property arising due to electron conjugation, highlighting antiaromaticity in tetracyclones. A systematic study of six tetracyclone derivatives with electron withdrawing and electron donating substituents has been carried out using experimental and theoretical charge density analysis. A three pronged approach based on quantum theory of atoms in molecules (QTAIM), nucleus independent chemical shifts (NICS), and source function (SF) has been employed to establish the degree of antiaromaticity of the central five-membered ring in all the derivatives. Electrostatic potentials mapped on the is density surface reveal the finer effects of different electron withdrawing and electron donating substituents on the carbonyl group. Chapter 2 presents a temperature induced reversible first order single crystal to single crystal phase transition (Room temperature Orthorhombic, P22121 to low temperature Monoclinic, P21) in a  hybrid peptide, Boc-γ4(R)Val-Val-OH. The thermal behavior accompanying the phase transition of the dipeptide crystal was characterized by differential scanning calorimetry, visual changes in birefringence of the sample during heating and cooling cycles on a hot-stage microscope with polarized light. Variable-temperature unit cell check measurements from 300 to 100 K showed discontinuity in the volume and cell parameters near the transition temperature, supporting the first-order behavior. The reversible nature of the phase transition is traced to be due to an interplay between enthalpy and entropy. Chapter 3 brings out an unusual stabilizing interaction involving a cooperative -hole and ¬hole character in a short NCS···NCS bond. This chapter describes structural features of four isothiocyanate derivatives, FmocXCH2NCS; X=Leu, Ile, Val and Ala. Among these it is observed that only FmocLeuCH2NCS which crystallizes in a tetragonal space group, P41, (a=b=12.4405(5) Å; c= 13.4141(8) Å) transforms isomorphously to a low temperature form, P41, (a=b=17.4665(1) Å; c= 13.1291(1) Å). The characteristics of the phase transition have been monitored by Differential Scanning Calorimetry, variable temperature IR and temperature dependent unit cell measurements. The short NCS···NCS intermolecular interaction (3.296(1) Å) is analyzed based on detailed experimental charge density analysis which reveals the nature of this stabilizing interaction. Chapter 4 explains a comparative study of syn and anti conformations of carboxylic acids in peptides from both structural aspect and charge density features. Single crystal structures of four peptides having syn conformations [BocLeuγ4(R)Valγ4(R)ValOH, BocLeuγ4(R)ValLeuγ4(R)ValOH, Boc3(S)Leu3(S)LeuOH] and one with anti conformation, BocLeuγ4(R)ValValOH have been analyzed. Experimental charge density analysis has been carried out exclusively on BocLeuγ4(R)ValValOH having anti form, because of its rare occurrence in literature. However, low temperature datasets on the four peptides with syn conformations were collected and theoretical charge density analysis has been carried out on two of these compounds. Electrostatic potentials mapped on is density surface bring out a significant difference at the oxygen atoms of the carboxyl group in the two conformations. However, lone pair orientation of different types of Oxygen atoms in the two forms (urethane, amide, acid) doesn’t exclusively indicate the differences in the corresponding charge density features. Chapter 5 addresses the issue of how sensitive are the charge density features associated with amino acid residues when the backbone conformational angles are varied. Three model systems, 1, L-alanyl–L-alanyl–L-alanine dehydrate; 2, anhydrous L-alanyl–L-alanyl–L¬alanine and 3, cyclo-(D,L-Pro)2(L-Ala)4 monohydrate have been chosen for this evaluation. Compound 1 has ant parallel alignment of tripe tide strands, and compound 2 has parallel alignment. All the alanine residues in compound 1 and 2 are in the -sheet region of the Ramachandran plot, whereas, the four Alanine residues in the cyclic hex peptide 3 span different regions of the Ramachandran plot. Theoretical multipole modelling has been carried out in order to explore the plausibility of transferring multipole parameters across different regions of Ramachandran Plot. Appendix I contains a brief description of charge shift bonding in Ph-CH2-Se-Se-CH2-Ph, as determined based on both experimental and theoretical charge density analysis. Appendix II contains a reprint of a published article on “Conformation-Changing Aggregation in Hydroxyacetone: A Combined Low-Temperature FTIR, Jet, and Crystallographic Study”.

In this dissertation, we employ a number of computational methods, including Ab Initio, Density Functional Theory, and Molecular Dynamics simulations to investigate key microscopic parameters that govern charge-transport and charge-generation in single-component and bimolecular charge-transfer organic semiconductors. First, electronic (transfer integrals, bandwidths, effective masses) and electron-phonon couplings of single-component organic semiconductors are discussed. In particular, we evaluate microscopic charge-transport parameters in a series of nonlinear acenes with extended pi-conjugated cores. Our studies suggest that high charge-carrier mobilities are expected in these materials, since large electronic couplings are obtained and the formation of self-localized polarons due to local and nonlocal electron-phonon couplings is unlikely. Next, we evaluate charge detrapping due to interaction with intra-molecular crystal vibrations in order to explain changes in experimentally measured electric conductivity generated by pulse excitations in the IR region of a photoresistor based on pentacene/C60 thin film. Here, we directly relate the nonlocal electron-phonon coupling constants with variations in photoconductivity. In terms of charge-generation from an excited manifold, we evaluate the modulation of the state couplings between singlet and triplet excited states due to crystal vibrations, in order to understand the effect of lattice vibrations on singlet fission in tetracene crystal. We find that the state coupling between localized singlet and correlated triplet states is much more strongly affected by the dynamical disorder due to lattice vibrations than the coupling between the charge-transfer singlet and triplet states. Next, the impact of Hartree-Fock exchange in the description of transport properties in crystalline organic semiconductors is discussed. Depending on the nature of the electronic coupling, transfer integrals and bandwidths can show a significant increase as a function of the amount of the Hartree-Fock exchange included in the functional. Similar trend is observed for lattice relaxation energy. It is also shown that the ratio between electronic coupling and lattice relaxation energy is practically independent of the amount of the Hartree-Fock exchange, making this quantity a good candidate for incorporation into tight-binding transport models. We also demonstrate that it is possible to find an amount of the Hartree-Fock exchange that recovers (quasi-particle) band structure obtained from a highly accurate G0W0 approach. Finally, a microscopic understanding of a phase transition in charge-carrier mobility from temperature independent to thermally activated in stilbene-tetrafluoro-tetracyanoquinodimethane crystal is provided.

In this thesis, a first-principles methodology to investigate the impact of electron-phonon interactions on the charge-carrier mobilities in organic molecular crystals has been developed. Well-known organic materials such as oligoacene and oligothienoacene derivatives were studied in detail. The nature of the intramolecular vibronic coupling in oligoacenes and oligothienoacenes was studied using an approach that combines high-resolution gas-phase photo-electron spectroscopy measurements with first-principles quantum-mechanical calculations. The electron interactions with optical phonons in oligoacene single crystals were investigated using both density functional theory and empirical force field methods. The low-frequency optical modes are found to play a significant role in dictating the temperature dependence of the charge-transport properties in the oligoacene crystals. The microscopic charge-transport parameters in the pentathienoacene, 1,4-diiodobenzene, and 2,6-diiodo-dithieno[3,2-<i>b</i>:2',3'-<i>d</i>]thiophene crystals were also investigated. It was found that the intrinsic charge transport properties in the pentathienoacene crystal might be higher than that in two benchmark high-mobility organic crystals, i.e., pentacene and sexithienyl. For 1,4-diiodobenzene crystal, a detailed quantum-mechanical study indicated that its high mobility is primarily associated with the iodine atoms. In the 2,6-diiododithieno[3,2-<i>b</i>:2',3'-<i>d</i>]thiophene crystal, the main source of electronic interactions were found along the π-stacking direction. For negatively charged carriers, the halogen-functionalized molecular crystals show a very large polaron binding energy, which suggests significantly low charge-transport mobility for electrons.

Thesis (MSc)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Organic molecular salts have a wide range of physical properties which can be chemically tailored by minor variations of their substituents. These characteristics include high degrees of anisotropy, electrical conductivity ranging from superconducting to insulating, and structural changes in the crystal lattice during first order phase transitions brought about by minimal changes in temperature, effective pressure, and in some cases even light. Hence, these materials are particularly interesting for the development of molecular electronics and also as study materials in solid state physics. The family of copper-dimethyl-dicyanoquinone-diimine (Cu(DMe-DCNQI)2) salts forms part of the radical anion salt subclass of organic molecular crystals and is of particular interest due to its extraordinarily high conductivity compared to other quasi one-dimensional organic conductors. Its metal-to-insulator phase transition is characterised by conductivity jumps across several orders of magnitude within a few kelvin. Over the past three decades the metallic and insulating phases, as well as the transition behaviour have been investigated extensively utilising a broad spectrum of methods amongst others electrical conductivity, electron spin resonance, and re ectivity measurements, x-ray photoelectron and infrared spectroscopy, x-ray diffraction, and dilatometry. Fast light-switching between phases has been observed in partially deuterated forms of Cu(DCNQI)2 on sub-100-ps time scales. Furthermore, the phase transition is believed to be induced by a deformation of the crystalline lattice and a charge density wave formation which are detectable in diffraction images. Therefore we want to investigate this metal-to-insulator phase transition structurally and temporally via ultrafast electron diffraction. The technique of ultrafast electron diffraction employs the fundamentals of pump-probe spectroscopy: One of the two femtosecond pulsed laser beams excites the thin, crystalline sample, while the other - after being converted into a pulsed electron beam via the photoelectric effect - forms a diffraction image of the sample's lattice structure. The arrival time of the two pulses at the sample can be varied by a few femtoseconds with respect to each other enabling the resolution of ultrafast structural dynamics of the crystal's atomic lattice via electron diffraction. During the work presented in this thesis the sample preparation and characterisation leading to a successful introduction of Cu(DCNQI)2 into our ultrafast electron diffraction setup is presented. A diffraction pattern of comparable quality to that of a commercially available transmission electron microscope was recorded of the metallic state of partially deuterated d6 Cu(DCNQI)2. Subsequent analysis of the obtained diffraction data and further studies of the low temperature state { including simulations as well as experiments { have narrowed down the factors still making the diffraction pattern evasive. Possible solutions to experimental challenges are proposed to make the documentation of structural ultrafast dynamics in these organic molecular salts an attainable goal in the future. / AFRIKAANSE OPSOMMING: Organiese molekulêre soute het `n wye verskeidenheid van fisiese eienskappe wat chemies verander kan word deur geringe variasie in die samestelling van die sout. Hierdie eienskappe sluit in `n hoë graad van anisotropie, elektriese geleidingsvermoë wat strek van supergeleiding tot elektriese isolasie, en strukturele veranderinge in die kristalstruktuur tydens eerste orde fase-oorgange wat veroorsaak word deur geringe veranderinge in temperature, effektiewe druk en in sommige gevalle selfs lig. Gevolglik is hierdie material besonder interessant vir die ontwikkeling van molekulêre elektronika en ook as studiemateriaal in vastetoestandfisika. Die familie van koperdimetieldisianokinoondiimien (Cu(DMe-DCNQI)2) soute vorm `n deel van die radikaal-anioon-sout subklas van organiese molekulêre kristalle en is van besondere belang as gevolg van hulle buitengewone hoë elektriese geleidingsvermoë in vergelyking met ander kwasi-eendimensionele organiese geleiers. Die metaal-na-isolator fase-oorgang van hierdie kristal word gekenmerk deur die verandering van die geleidingsvermoë met verskeie ordegroottes binne `n paar kelvin. Gedurende die laaste drie dekades is die metaal en isolator fases, asook die oorgangsgedrag deeglik ondersoek met behulp van `n wye verskeidenheid van metodes wat onder andere elektriese geleidingsvermoë, elektron-spin resonans en reeksiemetings, x-straal fotoelektron en infrarooi spektroskopie, x-straal diffraksie en dilatometrie insluit. Vinnige skakeling tussen fases is waargeneem in gedeeltelik gedeuteerde vorms van Cu(DCNQI)2 op `n sub-100-ps tydskaal. Daar word verder geglo dat die fase-oorgang geïnduseer word deur `n deformasie van die kristalstruktuur en die vorming van `n ladingsdigtheidgolf wat meetbaar is in elektrondiffraksiebeelde. Om hierdie rede wil ons die metaal-na-isolator fase-oorgang se struktuur- en tydafhanklikheid ondersoek deur gebruik te maak van ultra-vinnige elektron diffraksie. Die tegniek van ultra-vinnige elektron diffraksie maak gebruik van die beginsels van pomp-toets spektroskopie: Een van die twee femtosekonde laserpulse wek die dun kristallyne monster op, terwyl die ander na omskakeling in `n elektronpuls via die foto-elektriese effek `n diffraksiebeeld van die monster se kristalstruktuur vorm. Die aankomtyd van die twee pulse by die monster kan met `n paar femtosekondes ten opsigte van mekaar verander word om die tydresolusie van die ultra-vinnige strukturele dinamika van die kristal se atoomstruktuur deur elektrondiffraksie moontlik te maak. In hierdie tesis word die monstervoorbereiding en karakterisering wat gelei het tot suksesvolle eksperimente op Cu(DCNQI)2 in ons ultra-vinnige elektron diffraksie opstelling behandel. `n Diffraksie patroon waarvan die kwaliteit vergelykbaar is met die van `n kommersiëel beskikbare transmissie elektron mikroskoop is gemeet vir die metaalfase van gedeeltelik gedeuteerde d6 Cu(DCNQI)2. Daaropvolgende analiese van die gemete diffraksiedata en verdere studies van die lae temperatuur toestand wat simulasies sowel as eksperimente insluit het `n klein aantal faktore uitgewys wat steeds die deteksie van die isolatorfase se ladingsdigtheidgolf se kenmerkende diffraksiepatroon verhoed. Moontlike oplossings tot eksperimentele uitdagings word voorgestel om die dokumentering van strukturele ultra-vinnige dinamika in hierdie organiese molekulêre soute `n haalbare toekomstige doelwit te maak.

Electron-lattice interactions are often considered not to play a major role in material's properties as they are assumed to be small, the second-order effects. However, this study shows the importance of taking these effects into account in the simulations. My results demonstrate the impact of the electron-lattice interaction on the physics of the material and our understanding from it. One way to study these effects is to add them as perturbations to the unperturbed Hamiltonians in numerical simulations. The main objective of this thesis is to study electron-lattice interactions in molecular and magnetic crystals. It is devoted to developing numerical techniques considering model Hamiltonians and first-principles calculations to include the effect of lattice vibrations in the simulations of the above mentioned classes of materials. In particular, I study the effect of adding the non-local electron-phonon coupling on top of the Holstein Hamiltonian to study the polaron stability and polaron dynamics in molecular crystals. The numerical calculations are based on the semi-empirical Holstein-Peierls model in which both intra (Holstein) and inter (Peierls) molecular electron-phonon interactions are taken into account. I study the effect of different parameters including intra and intermolecular electron-phonon coupling strengths and their vibrational frequencies, the transfer integral and the electric field on polaron stability. I found that in an ordered two dimensional molecular lattice the polaron is stable for only a limited range of parameter sets with the polaron formation energies lying in the range between 50 to 100 meV. Using the stable polaron solutions, I applied an electric field to the system and I observed that the polaron is dynamically stable and mobile for only a limited set of parameters. Adding disorder to the system will result in even more restricted parameter set space for which the polaron is stable and moves adiabatically with a constant velocity. In order to study the effect of temperature on polaron dynamics, I include a random force in Newtonian equations of motion in a one dimensional molecular lattice. I found that there is a critical temperature above which the polaron destabilizes and becomes delocalized. Moreover, I study the role of lattice vibrations coupled to magnetic degrees of freedom in finite temperature paramagnetic state of magnetic materials. Calculating the properties of paramagnetic materials at elevated temperatures is a cumbersome task. In this thesis, I present a new method which allows us to couple lattice vibrations and magnetic disorder above the magnetic transition temperature and treat them on the same footing. The method is based on the combination of disordered local moments model and ab initio molecular dynamics (DLM-MD). I employ the method to study different physical properties of some model systems such as CrN and NiO in which the interaction between the magnetic and lattice degrees of freedom is very strong making them very good candidates for such a study. I calculate the formation energies and study the effect of nitrogen defects on the electronic structure of paramagnetic CrN at high temperatures. Using this method I also study the temperature dependent elastic properties of paramagnetic CrN. The results highlight the importance of taking into account the magnetic excitations and lattice vibrations in the studies of magnetic materials at finite temperatures. A combination of DLM-MD with another numerical technique namely temperature dependent effective potential (TDEP) method is used to study the vibrational free energy and phase stability of CrN. We found that the combination of magnetic and vibrational contributions to the free energy shifts down the phase boundary between the cubic paramagnetic and orthorhombic antiferromagnetic phases of CrN towards the experimental value. I used the stress-strain relation to study the temperature-dependent elastic properties of paramagnetic materials within DLM-MD with CrN as my model system. The results from a combinimation of DLM-MD with another newly developed method, symmetry imposed force constants (SIFC) in conjunction with TDEP is also presented as comparison to DLM-MD results.I also apply DLM-MD method to study the electronic structure of NiO in its paramagnetic state at finite temperatures. I found that lattice vibrations have a prominent impact on the electronic structure of paramagnetic NiO at high temperatures and should be included for the proper description of the density of states. In summary, I believe that the proposed techniques give reliable results and allow us to include the effects from electron-lattice interaction in simulations of materials.