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Full-Text Articles in Physical Sciences and Mathematics
Driving Piezochromism And Metallicity In Van Der Waals Materials Under Compression, Nathan Harms
Driving Piezochromism And Metallicity In Van Der Waals Materials Under Compression, Nathan Harms
Doctoral Dissertations
Complex chalcogenides provide an important platform to explore the interplay between structure, charge, and spin across pressure-induced phase transitions. Where much of the previous research has been focused on tuning these materials towards the single-layer limit, we instead explore the modification of bond lengths and bond angles under compression. In the first project we revealed piezochromism in MnPS3. We combined high pressure optical spectroscopy and first-principles calculations to analyze the dramatic color change (green → yellow → red → black) that takes place as the charge gap shifts across the visible and into the near infrared region, moving …
Symmetry Progression And Possible Polar Metallicity In Nips3 Under Pressure, Nathan Harms, Takahiro Matsuoka, Subhasis Sanmanta, Amanda J. Clune, Kevin A. Smith, Amanda V. Haglund, Erxi Feng, Huibo Cao, Jesse S. Smith, David Mandrus, Heung-Sik Kim, Zhenxian Liu, Janice L. Musfeldt
Symmetry Progression And Possible Polar Metallicity In Nips3 Under Pressure, Nathan Harms, Takahiro Matsuoka, Subhasis Sanmanta, Amanda J. Clune, Kevin A. Smith, Amanda V. Haglund, Erxi Feng, Huibo Cao, Jesse S. Smith, David Mandrus, Heung-Sik Kim, Zhenxian Liu, Janice L. Musfeldt
Chemistry Publications and Other Works
van der Waals solids are ideal platforms for the discovery of new states of matter and emergent properties under external stimuli. Under pressure, complex chalcogenides like MPS3 (M = Mn, Ni, Co, V) host sliding and structural transitions, insulator-to-metal transitions, the possibility of an orbitally-selective Mott state, piezochromism, and superconductivity. In this work, we bring together diamond anvil cell techniques, infrared and Raman scattering spectroscopies, and X-ray diffraction with a detailed symmetry analysis and first-principles calculations to uncover a series of high-pressure phases in NiPS3. Remarkably, we find five different states of matter between ambient …
The Exploration Of Small Molecules, Lanthanide Complexes, And Catalysis Using Electronic Structure Theory, Dynamics, And Machine Learning, Gavin Mccarver
The Exploration Of Small Molecules, Lanthanide Complexes, And Catalysis Using Electronic Structure Theory, Dynamics, And Machine Learning, Gavin Mccarver
Doctoral Dissertations
With the ever increasing availability of computational resources, more challenging chemical systems can be studied. Among these challenges are the rotational and vibrational spectra of diatomic molecules within spectroscopic accuracy, the environmental perturbations induced on a rotating water molecule, the prediction of free binding energies of lanthanide complexes using machine learning, and the study of catalytic mechanisms through a theoretical framework. High levels of electronic structure theory were combined with a rigorous treatment of either the anharmonic vibrational wave functions to study diatomic molecules or the rotational wave functions to study H2O-pH2 interactions. The former was initially …
Mining Uranium From Seawater: A Coordination Chemistry Approach, Nada Mehio
Mining Uranium From Seawater: A Coordination Chemistry Approach, Nada Mehio
Doctoral Dissertations
Poly(acrylamidoxime) fibers are the current state-of-the-art adsorbent for mining uranium from seawater. However, the amidoxime group is not perfectly selective towards the uranyl cation, in particular, competition with transition metal cations remains a major challenge. In order for subsequent generations of chelating polymer adsorbents to be improved, the coordination chemistry of amidoxime-uranyl and -transition metal cation complexes needs to be better understood. While the coordination mode of amidoxime-uranyl complexes has been established in the literature, a number of amidoxime-transition metal cation complex binding motifs can be observed on the Cambridge Structrural Database. Likewise, the formation constants, or log K values, …
A Six-Dimensional H2–H2 Potential Energy Surface For Bound State Spectroscopy, Robert Hinde
A Six-Dimensional H2–H2 Potential Energy Surface For Bound State Spectroscopy, Robert Hinde
Chemistry Publications and Other Works
We present a six-dimensional potential energy surface for the (H2)2 dimer based on coupled-cluster electronic structure calculations employing large atom-centered Gaussian basis sets and a small set of midbond functions at the dimer’s center of mass. The surface is intended to describe accurately the bound and quasibound states of the dimers (H2)2, (D2)2, and H2–D2 that correlate with H2 or D2 monomers in the rovibrational levels (v, j) =(0,0), (0,2), (1,0), and (1,2). We employ a close-coupled approach to compute the …
Infrared-Active Vibron Bands Associated With Substitutional Impurities In Solid Parahydrogen, Robert Hinde
Infrared-Active Vibron Bands Associated With Substitutional Impurities In Solid Parahydrogen, Robert Hinde
Chemistry Publications and Other Works
We present a model for the line shapes of infrared-active Q1(0) vibron bands observed in solid parahydrogen doped with low concentrations of spherical substitutional impurities. The line shapes are highly sensitive to the H2 vibrational dependence of the dopant–H2 interaction. When this vibrational dependence is strong, the dopant can trap the infrared-active vibron in its first solvation shell; in this case, the trapped vibron manifests itself in the absorption spectrum as a narrow feature to the red of the pure solid’s vibron band.