Publications
559 results found
Hendon CH, Carbery DR, Walsh A, 2014, 21st century misconceptions in fundamental organic chemistry: Cumulenes, oligoynes and 3-electron 2-centred bonds, 247th National Spring Meeting of the American-Chemical-Society (ACS), Publisher: AMER CHEMICAL SOC, ISSN: 0065-7727
Hendon CH, Walsh A, 2014, Electronic design principles of metal-organic frameworks for photocatalysis, gas-storage and light harvesting, 247th National Spring Meeting of the American-Chemical-Society (ACS), Publisher: AMER CHEMICAL SOC, ISSN: 0065-7727
Butler KT, Hendon CH, Walsh A, 2014, Electronic chemical potentials of porous metal-organic frameworks, Journal of the American Chemical Society, Vol: 136, Pages: 2703-2706, ISSN: 0002-7863
The binding energy of an electron in a material is a fundamental characteristic, which determines a wealth of important chemical and physical properties. For metal–organic frameworks this quantity is hitherto unknown. We present a general approach for determining the vacuum level of porous metal–organic frameworks and apply it to obtain the first ionization energy for six prototype materials including zeolitic, covalent, and ionic frameworks. This approach for valence band alignment can explain observations relating to the electrochemical, optical, and electrical properties of porous frameworks.
Buckeridge J, Scanlon DO, Veal TD, et al., 2014, N incorporation and associated localized vibrational modes in GaSb, PHYSICAL REVIEW B, Vol: 89, ISSN: 1098-0121
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- Citations: 14
Hendon CH, Carbery DR, Walsh A, 2014, Three-electron two-centred bonds and the stabilisation of cationic sulfur radicals, Chemical Science, Vol: 5, Pages: 1390-1395, ISSN: 2041-6539
Electronic communication in biological systems is fundamental to understanding protein signalling and electron hopping pathways. Frequently studied examples are cationic radical methionine and its functional derivatives. These systems are understood to be stabilised by a direct ‘three-electron two-centred’ bond. We demonstrate for methionine and a series of cationic radical methionine analogues that long-range multi-centred indirect stabilisation occurs, which cannot be attributed to three-electron two-centred interactions. A revised description of the radical stabilisation process is presented, which includes contributions from all atoms with accessible p-orbitals, independent of the distance to the sulfur radical.
Shibuya T, Goto Y, Kamihara Y, et al., 2014, From kesterite to stannite photovoltaics: Stability and band gaps of the Cu-2(Zn,Fe)SnS4 alloy, Applied Physics Letters, Vol: 104, ISSN: 1077-3118
Kesterite semiconductors, particularly Cu 2ZnSnS4 (CZTS), have attracted attention for thin-film solar cells. We investigate the incorporation of Fe into CZTS to form the Cu 2(Zn,Fe)SnS4 solid-solution for tuning the lattice spacing and band gap. First-principles calculations confirm a phase transition from kesterite (Zn-rich) to stannite (Fe-rich) at Fe/Zn ∼ 0.4∼ 0.4 . The exothermic enthalpy of mixing is consistent with the high solubility of Fe in the lattice. There is a linear band-gap bowing for each phase, which results in a blue-shift of photo-absorption for Fe-rich alloys due to the confinement of the conduction states. We propose compositions optimal for Si tandem cells.
Buckeridge J, Scanlon DO, Walsh A, et al., 2014, Automated procedure to determine the thermodynamic stability of a material and the range of chemical potentials necessary for its formation relative to competing phases and compounds, COMPUTER PHYSICS COMMUNICATIONS, Vol: 185, Pages: 330-338, ISSN: 0010-4655
Bolton EM, Tuzova AV, Walsh AL, et al., 2014, Noncoding RNAs in prostate cancer: the long and the short of it., Clin Cancer Res, Vol: 20, Pages: 35-43
As the leading culprit in cancer incidence for American men, prostate cancer continues to pose significant diagnostic, prognostic, and therapeutic tribulations for clinicians. The vast spectrum of disease behavior warrants better molecular classification to facilitate the development of more robust biomarkers that can identify the more aggressive and clinically significant tumor subtypes that require treatment. The untranslated portion of the human transcriptome, namely noncoding RNAs (ncRNA), is emerging as a key player in cancer initiation and progression and boasts many attractive features for both biomarker and therapeutic research. Genetic linkage studies show that many ncRNAs are located in cancer-associated genomic regions that are frequently deleted or amplified in prostate cancer, whereas aberrant ncRNA expression patterns have well-established links with prostate tumor cell proliferation and survival. The dysregulation of pathways controlled by ncRNAs results in a cascade of multicellular events leading to carcinogenesis and tumor progression. The characterization of RNA species, their functions, and their clinical applicability is a major area of biologic and clinical importance. This review summarizes the growing body of evidence, supporting a pivotal role for ncRNAs in the pathogenesis of prostate cancer. We highlight the most promising ncRNA biomarkers for detection and risk stratification and present the state-of-play for RNA-based personalized medicine in treating the "untreatable" prostate tumors.
Yoo S-H, Walsh A, Scanlon DO, et al., 2014, Electronic structure and band alignment of zinc nitride, Zn<sub>3</sub>N<sub>2</sub>, RSC ADVANCES, Vol: 4, Pages: 3306-3311
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- Citations: 35
Burton LA, Colombara D, Abellon RD, et al., 2013, Synthesis, Characterization, and Electronic Structure of Single-Crystal SnS, Sn2S3, and SnS2, Chemistry of Materials, Vol: 25, Pages: 4908-4916, ISSN: 1520-5002
Tin sulfide is being widely investigated as an earth-abundant light harvesting material, but recorded efficiencies for SnS fall far below theoretical limits. We describe the synthesis and characterization of the single-crystal tin sulfides (SnS, SnS2, and Sn2S3) through chemical vapor transport, and combine electronic structure calculations with time-resolved microwave conductivity measurements to shed light on the underlying electrical properties of each material. We show that the coexistence of the Sn(II) and Sn(IV) oxidation states would limit the performance of SnS in photovoltaic devices due to the valence band alignment of the respective phases and the “asymmetry” in the underlying point defect behavior. Furthermore, our results suggest that Sn2S3, in addition to SnS, is a candidate material for low-cost thin-film solar cells.
Lunt RA, Jackson AJ, Walsh A, 2013, Dielectric response of Fe<sub>2</sub>O<sub>3</sub> crystals and thin films, CHEMICAL PHYSICS LETTERS, Vol: 586, Pages: 67-69, ISSN: 0009-2614
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- Citations: 47
Jackson AJ, Walsh A, 2013, Oxidation of GaN: An <i>ab initio</i> thermodynamic approach, PHYSICAL REVIEW B, Vol: 88, ISSN: 2469-9950
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- Citations: 23
Walsh A, Scanlon DO, 2013, Polymorphism of indium oxide: Materials physics of orthorhombic In<sub>2</sub>O<sub>3</sub>, PHYSICAL REVIEW B, Vol: 88, ISSN: 2469-9950
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- Citations: 16
Brivio F, Walker AB, Walsh A, 2013, Structural and electronic properties of hybrid perovskites for high-efficiency thin-film photovoltaics from first-principles, APL MATERIALS, Vol: 1, ISSN: 2166-532X
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- Citations: 479
Buckeridge J, Bromley ST, Walsh A, et al., 2013, One-dimensional embedded cluster approach to modeling CdS nanowires, JOURNAL OF CHEMICAL PHYSICS, Vol: 139, ISSN: 0021-9606
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- Citations: 5
Walsh A, Butler KT, 2013, Prediction of Electron Energies in Metal Oxides, Accounts of Chemical Research, Vol: 47, Pages: 364-372, ISSN: 1520-4898
Scanlon DO, Dunnill CW, Buckeridge J, et al., 2013, Band alignment of rutile and anatase TiO<sub>2</sub>, NATURE MATERIALS, Vol: 12, Pages: 798-801, ISSN: 1476-1122
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- Citations: 1763
Hendon CH, Tiana D, Murray AT, et al., 2013, Helical frontier orbitals of conjugated linear molecules, Chemical Science, Vol: 4, Pages: 4278-4284, ISSN: 2041-6539
Compounds containing allenes, cumulenes and oligoynes (polyalkynes) have attracted attention for both their conformation and reactivity. Whilst the textbook molecular orbital description explains the general electronic and molecular structure of the cumulenes, there are anomalies in both the crystal structures and cycloaddition products involving oligoynes and allenes; the understanding of these molecules is incomplete. Through a computational study we elucidate that the frontier orbitals of the allene and oligoyne families are extended helices. These orbitals are the linear analogue to the Möbius aromatic systems, which also display non-linear π interactions. The axial chirality found in allenes and oligoynes is intimately related to the topology of the frontier orbitals, and has implications for predictions of cycloaddition pathways, structure stability and spectroscopy.
Walsh A, Buckeridge J, Catlow CRA, et al., 2013, Limits to Doping of Wide Band Gap Semiconductors, CHEMISTRY OF MATERIALS, Vol: 25, Pages: 2924-2926, ISSN: 0897-4756
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- Citations: 51
Allen JP, Carey JJ, Walsh A, et al., 2013, Electronic Structures of Antimony Oxides, JOURNAL OF PHYSICAL CHEMISTRY C, Vol: 117, Pages: 14759-14769, ISSN: 1932-7447
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- Citations: 70
Hendon CH, Tiana D, Fontecave M, et al., 2013, Engineering the Optical Response of the Titanium-MIL-125 Metal-Organic Framework through Ligand Functionalization, Journal of the American Chemical Society, Vol: 135, Pages: 10942-10945, ISSN: 1520-5126
Buckeridge J, Scanlon DO, Walsh A, et al., 2013, Dynamical response and instability in ceria under lattice expansion, PHYSICAL REVIEW B, Vol: 87, ISSN: 2469-9950
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- Citations: 43
Walsh A, Scanlon DO, 2013, Electron excess in alkaline earth sub-nitrides: 2D electron gas or 3D electride?, Journal of Materials Chemistry C, Vol: 1, Pages: 3525-3528, ISSN: 2050-7534
Alkaline earth sub-nitrides were synthesised more than five decades ago, but their potential for high-performance electronics was only recently demonstrated [Lee et al., Nature, 2013]. Based on the formal valence of the elements, there is an intrinsic excess of electrons, which is unusual for a chemically stable compound. We report an electrostatic and electronic analysis of Ca2N, Sr2N and Ba2N, which reveals a highly anisotropic electronic band structure, with a subtle balance between localisation and delocalisation of excess electrons in between positively charged planes of [M2N]+. A deep potential well is found at empty crystallographic positions, which are occupied by anions in the structurally analogous ternary nitrides. A greater degree of delocalisation (conductivity) is predicted for heavier metals.
Bristow JK, Parker SC, Catlow CRA, et al., 2013, Microscopic origin of the optical processes in blue sapphire, Chemical Communications, Vol: 49, Pages: 5259-5261, ISSN: 1364-548X
Al2O3 changes from transparent to a range of intense colours depending on the chemical impurities present. In blue sapphire, Fe and Ti are incorporated; however, the chemical process that gives rise to the colour has long been debated. Atomistic modelling identifies charge transfer from Ti(III) to Fe(III) as being responsible for the characteristic blue appearance.
Walsh A, Sokol AA, Catlow RRAC, 2013, Computational Approaches to Energy Materials, ISBN: 9781119950936
The development of materials for clean and efficient energy generation and storage is one of the most rapidly developing, multi-disciplinary areas of contemporary science, driven primarily by concerns over global warming, diminishing fossil-fuel reserves, the need for energy security, and increasing consumer demand for portable electronics. Computational methods are now an integral and indispensable part of the materials characterisation and development process. Computational Approaches to Energy Materials presents a detailed survey of current computational techniques for the development and optimization of energy materials, outlining their strengths, limitations, and future applications. The review of techniques includes current methodologies based on electronic structure, interatomic potential and hybrid methods. The methodological components are integrated into a comprehensive survey of applications, addressing the major themes in energy research. Topics covered include: Introduction to computational methods and approaches. Modelling materials for energy generation applications: solar energy and nuclear energy. Modelling materials for storage applications: batteries and hydrogen. Modelling materials for energy conversion applications: fuel cells, heterogeneous catalysis and solid-state lighting. Nanostructures for energy applications. This full colour text is an accessible introduction for newcomers to the field, and a valuable reference source for experienced researchers working on computational techniques and their application to energy materials. This edition first published 2013 © 2013 John Wiley & Sons, Ltd.
Catlow RRAC, Sokol AA, Walsh A, 2013, Computational Techniques, Computational Approaches to Energy Materials, Pages: 1-28, ISBN: 9781119950936
This chapter introduces fundamental computational approaches and ideas to energy materials. These can be divided into two main streams: one dealing with the motion of atoms or ions described at a simplified level of theory and another focusing on electrons. The modeling framework, which covers both streams, is outlined. The atomistic simulation techniques discussed in the chapter are concerned with describing the energy landscape of individual atoms or ions, where classical mechanics can be usefully employed as the first successful approximation. Multiscale approaches could be the method of choice if one is interested in large molecules, inhomogeneous solids, complex environments or geometrical arrangements, systems that are far away from equilibrium or have particularly long evolution times. One of the principal objectives of atomistic simulations is to derive an accurate and coherent approach to the prediction of defect structure, energetics and properties. Two of the most widely employed methods are outlined. This edition first published 2013 © 2013 John Wiley & Sons, Ltd.
Vaid TP, Turner DL, Singh MP, et al., 2013, Synthetic efforts at electrically conducting MOFs, guided by computational chemistry, 245th National Spring Meeting of the American-Chemical-Society (ACS), Publisher: AMER CHEMICAL SOC, ISSN: 0065-7727
Burton LA, Walsh A, 2013, Band alignment in SnS thin-film solar cells: Possible origin of the low conversion efficiency, APPLIED PHYSICS LETTERS, Vol: 102, ISSN: 0003-6951
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- Citations: 126
Deng H-X, Wei S-H, Li S-S, et al., 2013, Electronic origin of the conductivity imbalance between covalent and ionic amorphous semiconductors, PHYSICAL REVIEW B, Vol: 87, ISSN: 2469-9950
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- Citations: 38
Chen S, Walsh A, Gong X-G, et al., 2013, Classification of Lattice Defects in the Kesterite Cu<sub>2</sub>ZnSnS<sub>4</sub> and Cu<sub>2</sub>ZnSnSe<sub>4</sub> Earth-Abundant Solar Cell Absorbers, ADVANCED MATERIALS, Vol: 25, Pages: 1522-1539, ISSN: 0935-9648
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- Citations: 1218
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