Philip B. Allen
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View article: Free Electron Theory for Thin Metal Films
Free Electron Theory for Thin Metal Films Open
Quantum free electrons, i.e. plane waves, with wavevector k, and occupancy constrained by the Pauli exclusion principle, are explained in all solid state physics texts. Although overly simplified, free-electron theory works surprisingly we…
View article: StARD9 is a novel lysosomal kinesin required for membrane tubulation, cholesterol transport and Purkinje cell survival
StARD9 is a novel lysosomal kinesin required for membrane tubulation, cholesterol transport and Purkinje cell survival Open
The pathological accumulation of cholesterol is a signature feature of Niemann–Pick type C (NPC) disease, in which excessive lipid levels induce Purkinje cell death in the cerebellum. NPC1 encodes a lysosomal cholesterol-binding protein, a…
View article: Nonlocal thermal transport modeling using the thermal distributor
Nonlocal thermal transport modeling using the thermal distributor Open
Thermal transport in a quasi-ballistic regime is determined not only by the local temperature $T(r)$, or its gradient $\nabla T(r)$, but also by temperature distribution at neighboring points. For an accurate description of non-local effec…
View article: Nonlocal Phonon Heat Transport Seen in 1-d Pulses
Nonlocal Phonon Heat Transport Seen in 1-d Pulses Open
Phonons are the main heat carriers in semiconductor devices. In small devices, heat is not driven by a local temperature gradient, but by local points of heat input and removal. This complicates theoretical modeling. Study of the propagati…
View article: Phonon Heat Transport Seen in Pulses
Phonon Heat Transport Seen in Pulses Open
The ballistic to diffusive crossover, that occurs when quasiparticles transport heat or charge, is important in small systems. Propagation of energy from an initial localized pulse provides a useful picture of the process. This paper looks…
View article: Phonon Boltzmann equation non-local in space and time: the partial failure of the generalized Fourier law
Phonon Boltzmann equation non-local in space and time: the partial failure of the generalized Fourier law Open
The purpose of this note is to clarify the solution of the non-local Peierls Boltzmann equation found by Hua and Lindsay (Phys. Rev. B 102, 104310 (2020)). They used methods of Cepellotti and Marzari. The response function "thermal distrib…
View article: Pharmacokinetics of Tenofovir following Intravaginal and Intrarectal Administration of Tenofovir Gel to Rhesus Macaques
Pharmacokinetics of Tenofovir following Intravaginal and Intrarectal Administration of Tenofovir Gel to Rhesus Macaques Open
Tenofovir gel (1%) is being developed as a microbicide for the prevention of human immunodeficiency virus (HIV) infection and has been shown to reduce transmission to women by 39%. The gel also prevents infection in macaques when applied i…
View article: Quantum Theory of Semiconductor Photo-Catalysis and Solar Water Splitting / Theory and Computation for Semiconductor Catalysis of Solar Water Splitting / Static and Dynamic Thermal Effects in Solids. Final Report
Quantum Theory of Semiconductor Photo-Catalysis and Solar Water Splitting / Theory and Computation for Semiconductor Catalysis of Solar Water Splitting / Static and Dynamic Thermal Effects in Solids. Final Report Open
This is the final report. The finished research was published in 27 journal papers listed below. The topics fall roughly into seven categories: Photochemistry of water at the GaN ($10\\bar{1}0$) surface; Quasiparticles: Band electrons and …
View article: Quasi-harmonic theory of thermal expansion
Quasi-harmonic theory of thermal expansion Open
Quasi-harmonic (QH) theory (QHT) is sometimes incorrectly understood as a misguided way to do a low-order theory of anharmonic effects in crystals. The original and most widely accepted meaning of QHT is the use of T=0 volume (V)-dependent…
View article: Resistivity of high pressure phosphorus phases
Resistivity of high pressure phosphorus phases Open
Simple cubic (sc) black phosphorus (denoted BP), stable at P>10GPa, seems an ordinary metal. It has electron-phonon-driven superconductivity with Tc 5-10 K. The A17 phase, stable at atmospheric pressure, has a narrow gap, becomes semimetal…
View article: Temperature in a Peierls-Boltzmann treatment of nonlocal phonon heat transport
Temperature in a Peierls-Boltzmann treatment of nonlocal phonon heat transport Open
In nonmagnetic insulators, phonons are the carriers of heat. If heat enters in a region and temperature is measured at a point within phonon mean free paths of the heated region, ballistic propagation causes a nonlocal relation between loc…
View article: Erratum: First-principles study of pyroelectricity in GaN and ZnO [Phys. Rev. B <b>93</b>, 081205(R) (2016)]
Erratum: First-principles study of pyroelectricity in GaN and ZnO [Phys. Rev. B <b>93</b>, 081205(R) (2016)] Open
Received 11 July 2018DOI:https://doi.org/10.1103/PhysRevB.98.039905©2018 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasPhononsPyroelectricityPhysical SystemsPyroelectricsTechniquesLDAPseudopotentialsCondensed Matte…
View article: Analysis of nonlocal phonon thermal conductivity simulations showing the ballistic to diffusive crossover
Analysis of nonlocal phonon thermal conductivity simulations showing the ballistic to diffusive crossover Open
Simulations (e.g. Zhou et al., Phys. Rev. B 79, 115201 (2009)) show nonlocal\neffects of the ballistic/diffusive crossover. The local temperature has\nnonlinear spatial variation not contained in the local Fourier law\n$\\vec{j}(\\vec{r})=…
View article: Quasiparticles and phonon satellites in spectral functions of semiconductors and insulators: Cumulants applied to the full first-principles theory and the Fröhlich polaron
Quasiparticles and phonon satellites in spectral functions of semiconductors and insulators: Cumulants applied to the full first-principles theory and the Fröhlich polaron Open
The electron-phonon interaction causes thermal and zero-point motion shifts of electron quasiparticle (QP) energies $\epsilon_k(T)$. Other consequences of interactions, visible in angle-resolved photoemission spectroscopy (ARPES) experimen…
View article: Quasiparticles and phonon satellites in spectral functions of semiconductors and insulators: Cumulants applied to full first principles theory and Fröhlich polaron
Quasiparticles and phonon satellites in spectral functions of semiconductors and insulators: Cumulants applied to full first principles theory and Fröhlich polaron Open
The electron-phonon interaction causes thermal and zero-point motion shifts of electron quasiparticle (QP) energies $ε_k(T)$. Other consequences of interactions, visible in angle-resolved photoemission spectroscopy (ARPES) experiments, are…
View article: Non-local phonon thermal conductivity
Non-local phonon thermal conductivity Open
Simulations (e.g. Zhou et al., Phys. Rev. B 79, 115201 (2009)) show nonlocal effects of the ballistic/diffusive crossover. The local temperature has nonlinear spatial variation not contained in the local Fourier law $\vec{j}(\vec{r})=-\kap…
View article: Non-local phonon thermal conductivity and the ballistic to diffusive crossover
Non-local phonon thermal conductivity and the ballistic to diffusive crossover Open
The local Fourier relation between heat current to temperature gradient, J = -kdT/dr, does not hold on length scales shorter than carrier mean free paths. In insulating crystals, long phonon mean free paths enhance nonlocality of the kerne…
View article: Influence of Fröhlich polaron coupling on renormalized electron bands in polar semiconductors: Results for zinc-blende GaN
Influence of Fröhlich polaron coupling on renormalized electron bands in polar semiconductors: Results for zinc-blende GaN Open
\\ni We develop a simple method to study the zero-point and thermally\nrenormalized electron energy $\\varepsilon_{\\mathbf{k}n}(T)$ for $\\mathbf{k}n$\nthe conduction band minimum or valence maximum in polar semiconductors. We use\nthe ad…
View article: Low temperature semiconductor band gap thermal shifts
Low temperature semiconductor band gap thermal shifts Open
At low temperature T, the experimental gap of silicon decreases as E_g(T)=E_g(0)-AT^4. The main reason is electron-phonon renormalization. The physics behind the T^4-power law is more complex than has been realized. Renormalization by intr…
View article: First-principles study of pyroelectricity in GaN and ZnO
First-principles study of pyroelectricity in GaN and ZnO Open
First-principles calculations are made for the primary pyroelectric coefficients of wurtzite GaN and ZnO. The pyroelectricity is attributed to the quasiharmonic thermal shifts of internal strains (internal displacements of cations and anio…
View article: First-principles study of pyroelectricity in GaN and ZnO
First-principles study of pyroelectricity in GaN and ZnO Open
First-principles calculations are made for the primary pyroelectric\ncoefficients of wurtzite GaN and ZnO. The pyroelectricity is attributed to the\nquasiharmonic thermal shifts of internal strains (internal displacements of\ncations and a…