We are engaged in theory and modeling of materials at the atomic scale. Our recent work has two primary directions:

1. Monolayer and few layer materials (i.e. graphene, MoS2) for electronics, NEMS, and energy applications.
2. Materials at conditions of high temperature, electromagnetic fields, and pressures, including dynamic or shock compression.

Recent research topics include piezoelectricity and phase change effects in monolayer materials. Past topics include THz radiation generation, energetic materials, and photonic crystals. We develop and utilize computational tools (molecular dynamics statistical methods, electronic structure, materials informatics approaches, etc.) and interact closely with experimentalists.

Academic Appointments

Honors & Awards

  • ONR Young Investigator Program Award (YIP), Office of Naval Research (2015)
  • NSF Career Award, NSF (2014)
  • Young Faculty Award, DARPA (2012)
  • Robert Noyce Faculty Scholar, Stanford University School of Engineering (2010-2013)
  • Ernest O. Lawrence Postdoctoral Fellow, Lawrence Livermore National Laboratory (2004 - 2007)

Professional Education

  • BS, Caltech, Applied Physics (1998)
  • PhD, MIT, Physics (2003)

2016-17 Courses

Stanford Advisees

All Publications

  • Quantum Nuclear Effects in Stishovite Crystallization in Shock-Compressed Fused Silica JOURNAL OF PHYSICAL CHEMISTRY C Shen, Y., Reed, E. J. 2016; 120 (31): 17759-17766
  • Structural semiconductor-to-semimetal phase transition in two-dimensional materials induced by electrostatic gating NATURE COMMUNICATIONS Li, Y., Duerloo, K. N., Wauson, K., Reed, E. J. 2016; 7


    Dynamic control of conductivity and optical properties via atomic structure changes is of technological importance in information storage. Energy consumption considerations provide a driving force towards employing thin materials in devices. Monolayer transition metal dichalcogenides are nearly atomically thin materials that can exist in multiple crystal structures, each with distinct electrical properties. By developing new density functional-based methods, we discover that electrostatic gating device configurations have the potential to drive structural semiconductor-to-semimetal phase transitions in some monolayer transition metal dichalcogenides. Here we show that the semiconductor-to-semimetal phase transition in monolayer MoTe2 can be driven by a gate voltage of several volts with appropriate choice of dielectric. We find that the transition gate voltage can be reduced arbitrarily by alloying, for example, for MoxW1-xTe2 monolayers. Our findings identify a new physical mechanism, not existing in bulk materials, to dynamically control structural phase transitions in two-dimensional materials, enabling potential applications in phase-change electronic devices.

    View details for DOI 10.1038/ncomms10671

    View details for Web of Science ID 000371021000023

    View details for PubMedID 26868916

  • Structural Phase Transitions by Design in Monolayer Alloys ACS NANO Duerloo, K. N., Reed, E. J. 2016; 10 (1): 289-297


    Two-dimensional monolayer materials are a highly anomalous class of materials under vigorous exploration. Mo- and W-dichalcogenides are especially unusual two-dimensional materials because they exhibit at least three different monolayer crystal structures with strongly differing electronic properties. This intriguing yet poorly understood feature, which is not present in graphene, may support monolayer phase engineering, phase change memory and other applications. However, knowledge of the relevant phase boundaries and how to engineer them is lacking. Here we show using alloy models and state-of-the-art density functional theory calculations that alloyed MoTe2-WTe2 monolayers support structural phase transitions, with phase transition temperatures tunable over a large range from 0 to 933 K. We map temperature-composition phase diagrams of alloys between pure MoTe2 and pure WTe2, and benchmark our methods to analogous experiments on bulk materials. Our results suggest applications for two-dimensional materials as phase change materials that may provide scale, flexibility, and energy consumption advantages.

    View details for DOI 10.1021/acsnano.5b04359

    View details for Web of Science ID 000369115800029

    View details for PubMedID 26647117

  • Piezoelectricity: Now in two dimensions. Nature nanotechnology Reed, E. J. 2015; 10 (2): 106-107

    View details for DOI 10.1038/nnano.2014.319

    View details for PubMedID 25531086

  • Strain engineering in monolayer materials using patterned adatom adsorption. Nano letters Li, Y., Duerloo, K. N., Reed, E. J. 2014; 14 (8): 4299-4305


    We utilize reactive empirical bond order (REBO)-based interatomic potentials to explore the potential for the engineering of strain in monolayer materials using lithographically or otherwise patterned adatom adsorption. In the context of graphene, we discover that the monolayer strain results from a competition between the in-plane elasticity and out-of-plane relaxation deformations. For hydrogen adatoms on graphene, the strain outside the adsorption region vanishes due to out-of-plane relaxation deformations. Under some circumstances, an annular adsorption pattern generates homogeneous tensile strains of approximately 2% in graphene inside the adsorption region, approximately 30% of the strain in the adsorbed region. We find that an elliptical adsorption pattern produces strains of as large as 5%, close to the strain in the adsorbed region. Also, nonzero maximum shear strain (∼4%) can be introduced by the elliptical adsorption pattern. We find that an elastic plane stress model provides qualitative guidance for strain magnitudes and conditions under which strain-diminishing buckling can be avoided. We identify geometric conditions under which this effect has potential to be scaled to larger areas. Our results elucidate a method for strain engineering at the nanoscale in monolayer devices.

    View details for DOI 10.1021/nl500974t

    View details for PubMedID 25051232

  • Structural phase transitions in two-dimensional Mo- and W-dichalcogenide monolayers NATURE COMMUNICATIONS Duerloo, K. N., Li, Y., Reed, E. J. 2014; 5


    Mo- and W-dichalcogenide compounds have a two-dimensional monolayer form that differs from graphene in an important respect: it can potentially have more than one crystal structure. Some of these monolayers exhibit tantalizing hints of a poorly understood structural metal-to-insulator transition with the possibility of long metastable lifetimes. If controllable, such a transition could bring an exciting new application space to monolayer materials beyond graphene. Here we discover that mechanical deformations provide a route to switching thermodynamic stability between a semiconducting and a metallic crystal structure in these monolayer materials. Based on state-of-the-art density functional and hybrid Hartree-Fock/density functional calculations including vibrational energy corrections, we discover that MoTe2 is an excellent candidate phase change material. We identify a range from 0.3 to 3% for the tensile strains required to transform MoTe2 under uniaxial conditions at room temperature. The potential for mechanical phase transitions is predicted for all six studied compounds.

    View details for DOI 10.1038/ncomms5214

    View details for Web of Science ID 000340611600002

    View details for PubMedID 24981779

  • Flexural Electromechanical Coupling: A Nanoscale Emergent Property of Boron Nitride Bilayers NANO LETTERS Duerloo, K. N., Reed, E. J. 2013; 13 (4): 1681-1686


    The symmetry properties of atomically thin boron nitride (BN) monolayers endow them with piezoelectric properties, whereas the bulk parent crystal of stacked BN layers is not piezoelectric. This suggests potential for unusual electromechanical properties in the few layer regime. In this work, we explore this regime and discover that a bilayer consisting of two BN monolayers exhibits a strong mechanical coupling between curvature and electric fields. Using a mechanical model with parameters obtained from density functional theory, we find that these bilayers amplify in-plane piezoelectric displacements by exceedingly large factors on the order of 10(3)-10(4). We find that this type of electromechanical coupling is an emergent nanoscale property that occurs only for the case of two stacked BN monolayers.

    View details for DOI 10.1021/nl4001635

    View details for Web of Science ID 000317549300051

  • Simulations of Shocked Methane Including Self-Consistent Semiclassical Quantum Nuclear Effects JOURNAL OF PHYSICAL CHEMISTRY A Qi, T., Reed, E. J. 2012; 116 (42): 10451-10459


    A methodology is described for atomistic simulations of shock-compressed materials that incorporates quantum nuclear effects on the fly. We introduce a modification of the multiscale shock technique (MSST) that couples to a quantum thermal bath described by a colored noise Langevin thermostat. The new approach, which we call QB-MSST, is of comparable computational cost to MSST and self-consistently incorporates quantum heat capacities and Bose-Einstein harmonic vibrational distributions. As a first test, we study shock-compressed methane using the ReaxFF potential. The Hugoniot curves predicted from the new approach are found comparable with existing experimental data. We find that the self-consistent nature of the method results in the onset of chemistry at 40% lower pressure on the shock Hugoniot than observed with classical molecular dynamics. The temperature shift associated with quantum heat capacity is determined to be the primary factor in this shift.

    View details for DOI 10.1021/jp308068c

    View details for Web of Science ID 000310120800022

    View details for PubMedID 23013329

  • Intrinsic Piezoelectricity in Two-Dimensional Materials JOURNAL OF PHYSICAL CHEMISTRY LETTERS Duerloo, K. N., Ong, M. T., Reed, E. J. 2012; 3 (19): 2871-2876

    View details for DOI 10.1021/jz3012436

    View details for Web of Science ID 000309505400023

  • Ultrafast Detonation of Hydrazoic Acid (HN3) PHYSICAL REVIEW LETTERS Reed, E. J., Rodriguez, A. W., Manaa, M. R., Fried, L. E., Tarver, C. M. 2012; 109 (3)


    The fastest self-sustained chemical reactions in nature occur during detonation of energetic materials where reactions are thought to occur on nanosecond or longer time scales in carbon-containing materials. Here we perform the first atomistic simulation of an azide energetic material, HN3, from the beginning to the end of the chemical evolution and find that the time scale for complete decomposition is a mere 10 ps, orders of magnitude shorter than that of secondary explosives and approaching the fundamental limiting time scale for chemistry; i.e., vibrational time scale. We study several consequences of the short time scale including a state of vibrational disequilibrium induced by the fast transformations.

    View details for DOI 10.1103/PhysRevLett.109.038301

    View details for Web of Science ID 000306466900025

    View details for PubMedID 22861903

  • Engineered Piezoelectricity in Graphene ACS NANO Ong, M. T., Reed, E. J. 2012; 6 (2): 1387-1394


    We discover that piezoelectric effects can be engineered into nonpiezoelectric graphene through the selective surface adsorption of atoms. Our calculations show that doping a single sheet of graphene with atoms on one side results in the generation of piezoelectricity by breaking inversion symmetry. Despite their 2D nature, piezoelectric magnitudes are found to be comparable to those in 3D piezoelectric materials. Our results elucidate a designer piezoelectric phenomenon, unique to the nanoscale, that has potential to bring dynamical control to nanoscale electromechanical devices.

    View details for DOI 10.1021/nn204198g

    View details for Web of Science ID 000300757900046

    View details for PubMedID 22196055

  • Electron-Ion Coupling in Shocked Energetic Materials JOURNAL OF PHYSICAL CHEMISTRY C Reed, E. J. 2012; 116 (3): 2205-2211

    View details for DOI 10.1021/jp206769c

    View details for Web of Science ID 000299584400022

  • Observation of terahertz radiation coherently generated by acoustic waves.  Nature Physics  Reed, E., J., Armstrong, M., R. et al. 2009; 5: 285-288

    View details for DOI 10.1038/nphys1219