Welcome to the repository for University of Maryland research.

The Digital Repository at the University of Maryland (DRUM) collects, preserves, and provides public access to the scholarly output of the university. Faculty and researchers can upload research products for rapid dissemination, global visibility and impact, and long-term preservation.

  • Faculty may use DRUM to fulfill the Equitable Access to Scholarly Articles Authored by University Faculty policy, and in many cases may use it to fulfill open access requirements from grant funding agencies.
  • Departments can use DRUM to publish or distribute their working papers, technical reports, or other research material.
  • DRUM also includes all UMD theses and dissertations from 2003 forward.

To learn more about DRUM submission guidelines, and how you can make your research openly accessible to the public, visit our DRUM policies website.

To submit an item to DRUM, login using your UMD credentials. Then select the "Submit Item to DRUM" link in the navigation bar.

 

Recent Submissions

Item
Understanding the Relationship between Crime and Temperature in the Chicago Region
(2024-01-24) Hans, Abhimanyu; Benjamin, Alice; Sharma, Ashish; Harp, Ryan; Veiga, Carolina; Budhathoki, Milan; Budhathoki, Milan
This study investigates the relationship between temperature and crime rates in Chicago over a 20-year period. Crime and temperature data were analyzed at the census tract level to examine spatial and temporal correlations. The study tested the hypothesis that certain crimes increase with warmer temperatures while others rise with colder temperatures, and that higher temperatures predict higher crime overall. Urban climate data from the Weather Research and Forecasting Model (WRF) and public crime data were compared to identify census tracts sensitive to seasonal temperature changes. Different crime types were found to correlate with a heat vulnerability index based on socioeconomic and health metrics. The findings aim to help law enforcement, urban planners, and stakeholders locate areas of heat stress and develop interventions to reduce violence and structured racism in highly crime-prone neighborhoods. This novel investigation of the overlooked links between climate, geography, and crime can inform strategies to mitigate urban heat impacts on public safety.
Item
Short-chain model of chemisorption: Exact and approximate results
(American Physical Society, 1975) Einstein, Theodore L.
The binding energy of an adatom to a chain consisting of three atoms is obtained exactly by computer as a function of adatom Coulomb repulsion, adatom-substrate hopping, and substrate bandwidth. Three simple approximations are also plotted: (i) weak-binding limit, in which the binding energy is given by the expectation value of the adatom-bulk hopping Hamiltonian calculated in second-order perturbation theory; (ii) rebonded surface complex, in which the adatom forms a diatomic molecule with its nearest neighbor in the chain, and the dimer rebonds perturbatively to the indented chain; and (iii) Hartree-Fock, both restricted and unrestricted. The first two schemes can be joined smoothly by hand, and the resulting curve is much better than Hartree-Fock. The physics of all three cases is carefully studied. An appendix treats the surface diatom case of just a single bulk atom. Here the exact solution and unrestricted Hartree-Fock can be performed analytically. Comparison is also given with Brenig and Schönhammer's solution based on Green's-function formalism with matrix self-energy corrections.
Item
Changes in density of states caused by chemisorption
(American Physical Society, 1975) Einstein, Theodore L.
The process of chemisorption is studied via the change in density of states when an adatom with a single level Ea bonds by a hopping parameter V to the (100) surface of an s-band simple cubic crystal. As V increases, the bond changes from a perturbative regime to the formation of a surface complex. Investigations of local and layer-summed show this dimerlike structure to be well localized near the bond. Steric effects (binding-site symmetry) are easily introduced. A damping parameter can be added to simulate decay effects of surface probes. Application of the model to photoemission angular-averaged and angular-resolved difference spectra for light gases on tungsten gives understanding of the bonding peak near the bottom of the band, of the depletion of states near the Fermi energy, and of the slight shifting of the energy-momentum-conserving peak.
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Indirect Interaction between Adatoms on a Tight-Binding Solid
(American Physical Society, 1973) Einstein, Theodore L.; Schrieffer, J. R.
The indirect interaction between adatom pairs on the (100) surface of a simple-cubic tight-binding solid is investigated within a molecular-orbital approach. A general scheme for calculating the surface-density-of-states change and the interaction energy of one and two single-level adatoms is presented, and contact (and a correction) is made with Grimley's formulation. The method permits binding above surface atoms, at bridge sites, or at centered positions, and yields interaction energy as a function of band filling, adatom energy level, and a general hopping potential V between an adatom and the nearest surface atom(s).
Item
Statistical Mechanics of a Simple Model of a Displacive Ferroelectric
(American Physical Society, 1973) Cohen, Michael; Einstein, Theodore L.