John D. Weeks

	Distinguished University Professor Ph.D. University of Chicago, 1969 B.A. Harvard College, 1965 Joint Appointment with Institute for Physical Science and Technology and Department of Chemistry and Biochemistry  Affiliate Professor: Department of Physics
Institute for Physical Science and Technology University of Maryland College Park, MD 20742-2021 phone (301) 405-4802 - fax (301) 314-9404 IPST  (Bldg. 085), Rm 1111  jdw at ipst.umd.edu

Awards

Fellow, American Physical Society, 1984
Distinguished Member of Technical Staff Award, Bell Laboratories, 1985
Joel Henry Hildebrand Award, American Chemical Society, 1990
Distinguished University Professor, University of Maryland, 1995 
Fellow, American Academy of Arts and Sciences, 2000 

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Research in my group is concentrated in two main areas. The first focuses on the static and dynamic properties of interfaces, concentrating in particular on the dynamics of steps on crystal surfaces. This link describes new experiments and theory for the motion of a noncentered screw dislocation that is confined to the circular top facet of a nanoscale lead crystallite supported on a Ruthenium substrate. As shown in the movies these crystallites relax by turning of the spiral step emerging from the screw dislocation.

The figure at the right shows step bunches caused by the adsorption of impurities on crystal surfaces during crystal growth. Click on the following to see movies and learn more about instabilities and patterns that can form during step motion. This research is supported by the National Science Foundation through the Materials Research Science and Engineering Center (MRSEC) at Maryland. 

The second main area focuses on the properties of inhomogeneous and confined fluids, and is supported by the National Science Foundation. Click here for more information. 

Both these areas involve properties of strongly interacting disordered systems, and we use the same fundamental methods of statistical mechanics to try to develop general quantitative theories that make contact with experiment. While we use computer simulations to refine and test our ideas, the main emphasis is on the development of new conceptual approaches where physical insight and intuition play an important role.

Recent Publications

Naidoo, K.J., Schnitker, J. and Weeks, J. D., "Two-Dimensional Melting Revisited: Molecular Dynamics Simulations Initiated with Optical Microscopy Data."  Mol. Phys. 80, 1-24 (1993). 

Kandel, D. and Weeks, J.D., "Theory of Impurity Induced Step Bunching."  Phys. Rev. B 49, 5554-5564 (1994). 

Weeks, J.D., "Modeling Research." Comp. Mat. Sci. 2, 81-84 (1994). 

Kandel, D. and Weeks, J.D., "Step Motion, Patterns and Kinetic Instabilities on Crystal Surfaces." Phys. Rev. Lett. 72, 1678-1681 (1994). 

D. Kandel and J. D. Weeks, "Simultaneous Bunching and Debunching of Surface Steps: Theory and Relation to Experiments." Phys. Rev. Lett. 74, 3632-3635 (1995). 

J. D. Weeks, R. L. B. Selinger, and J. Q. Broughton, "Self-Consistent Treatment of Repulsive and Attractive Forces in Nonuniform Liquids."  Phys. Rev. Lett. 75, 2694-2697 (1995). 

D. Kandel and J. D. Weeks, "Kinetics of Surface Steps in the Presence of Impurities:  Patterns and Instabilities," Phys. Rev. B.  52, 2154-2164 (1995).

H.-C. Jeong and J. D. Weeks, "Faceting Through the Propagation of Nucleation.'' Phys. Rev. Lett. 75, 4456-4459 (1995). 

E. S. Fu, M. D. Johnson, D.-J. Liu, J. D. Weeks, and E. D. Williams, "Size Scaling in the Decay of Metastable Structures." Phys. Rev. Lett. 77, 1091-1094 (1996). 

D.-J. Liu, R. L. B. Selinger, and J. D.Weeks, "Representing Molecular Shape and Interactions: A Reduced Intermolecular Potential For Copper Phthalocyanine."
J. Chem. Phys. 105 , 4751-4760 (1996) . 

D.-J. Liu, E. S. Fu, M. D. Johnson, J. D.Weeks, and E. D. Williams, "Relaxation of the Step Profile for Different Microscopic Mechanisms."
J. Vac.Sci. & Tech. B 14, 2799-2808 (1996). 

J.D. Weeks, D.-J. Liu, and H.-C. Jeong, "Two-Dimensional Models for Step Dynamics" in:  Dynamics of Crystal Surfaces and Interfaces, edited by P. Duxbuty and T. Spence (Plenum, New York) 1997, pp. 199-216. 

D.-J. Liu, J. D. Weeks, M. D. Johnson, and E. D.Williams, "Two-Dimensional Facet Nucleation and Growth on Si(111)." Phys. Rev. B 55, 7653-7659 (1997). 

J.D. Weeks, K. Vollmayr and K. Katsov, "Intermolecular Forces and the Structure of Uniform and Nonuniform Fluids." Physica A 244, 461-475 (1997). 

D.-J. Liu and J. D. Weeks, "Interactions between Fluctuating Steps on Vicinal Surfaces: Edge Energy Effects in Reconstruction Induced Faceting."
Phys. Rev. Lett. 79, 1694-1697 (1997). 

H.-C. Jeong and J. D. Weeks, "Two-Dimensional Dynamical Model for Step Bunching  and Pattern Formation Induced by Surface Reconstruction", Phys. Rev. B 57, 3939-3948  (1998).

D.-J. Liu and J. D. Weeks, "Quantitative Theory of Current-Induced Step Bunching on Si(111)." Phys. Rev. B 57 14891-14900 (1998).

D.-J. Liu, J. D. Weeks, and D. Kandel, "Current-Induced Step Bending Instability on Vicinal Surfaces", Phys. Rev Lett.  81, 2743-2746 (1998).

 J D. Weeks, K. Katsov, and K. Vollmayr, "Role of Repulsive and Attractive Forces in Determining the Structure of Nonuniform Liquids: Generalized Mean Field Theory", Phys. Rev. Lett.  81, 4400-4403 (1998).

K. Lum, D. Chandler and J. D. Weeks, "Hydrophobicity at Small and Large Length  Scales", J. Phys. Chem. B 103, 4570-4577 (1999).

H.-C. Jeong and J. D. Weeks, "Effect of Step-Step Interactions on the Fluctuations of an  Individual Step on a Vicinal Surface", Surf. Sci. 432, 101-114 (1999).

K. Thürmer, D-J. Liu, E. D. Williams, and J. D. Weeks, "Onset of Step Anti-Banding Instability due to Surface Electromigration",  Phys. Rev. Lett. 83, 5531-5534 (1999).

N. Israeli, H.-C. Jeong, D. Kandel, and J. D. Weeks, "Dynamics and Scaling of One Dimensional Surface Structures," Phys. Rev. B 61, 5698-5706 (2000).

K. Katsov and J. D. Weeks, "Determining Liquid Structure from the Tail of the Direct Correlation Function," J. Stat. Phys. 100, 107-134 (2000).

K. Vollmayr-Lee, K. Katsov, and J. D. Weeks, "Using Mean Field Theory to Determine the Structure of Uniform Fluids," J. Chem. Phys. 114, 416-425 (2001).

K. Katsov and J. D. Weeks, "Density Fluctuations and the Structure of a Nonuniform Hard Sphere Fluid," Phys. Rev. Lett.  86,  440-443 (2001).

K. Katsov and J. D. Weeks, "On the Mean Field Treatment of Attractive Interactions in Nonuniform Simple Fluids," J. Phys. Chem. B 105, 6738-6744 (2001).

J. D. Weeks, "Connecting Local Structure to Interface Formation: A Molecular Scale van der Waals Theory of Nonuniform Liquids," Annu. Rev. Phys. Chem. 53,  533-562 (2002).

J. D. Weeks, "External fields, Density Functionals, and the Gibbs Inequality," J. Stat. Phys. 110, 1209-1217 (2003).

K. Katsov and J. D. Weeks, "Incorporating Molecular Scale Structure into the van der Waals Theory of the Liquid-vapor Interface," J. Phys. Chem. 106,  8429-8436 (2002).

Y.-G. Chen and J. D. Weeks, "Different Thermodynamic Pathways to the Solvation Free Energy of a Spherical Cavity in a Hard Sphere Fluid," J. Chem. Phys. 118, 7944-7953 (2003)

J. D. Chai and J. D. Weeks, "Modified Statistical Treatment of Kinetic Energy in the Thomas-Fermi Model," J. Phys. Chem. B 108, 6870-6876 (2004).

T. Zhao, J. D. Weeks, and D. Kandel, "A Unified Treatment of Current-Induced Instabilities on Si Surfaces," Phys. Rev. B 70, 161303(R) 1-4 (2004).

T. Zhao, J. D. Weeks, and D. Kandel, "From Discrete Hopping to Continuum Modeling on Vicinal Surfaces with Applications to Si(001) Electromigration," Phys. Rev. B 71, 155326 1-9 (2005).

Y.-G. Chen, C. Kaur, and J. D. Weeks, "Connecting Systems with Short and Long Ranged Interactions: Local Molecular Field Theory for Ionic Fluids," J. Phys. Chem. B 108, 19874-19884 (2004).

T. Zhao and J. D. Weeks, "A Two-Region Diffusion Model for Current-Induced Instabilities of Step Patterns on Vicinal Si(111) Surfaces," Surface Science  580, 107-121 (2005).

Y.-G. Chen and J. D. Weeks, "Structure of Nonuniform Hard Sphere Fluids from Shifted Linear Truncations of Functional Expansions," J. Phys. Chem. B 109, 6892-6901 (2005).

M. Ranganathan, D. B. Dougherty, W. G. Cullen, T. Zhao, J. D. Weeks, and E. D. Williams, “Spiral Evolution in a Confined Geometry,” Phys. Rev. Lett. 95, 225505/1-4 (2005).

Y.-G. Chen and J. D. Weeks, “Local Molecular Field Theory for Effective Attractions Between Like-charged Objects in Systems with Strong Coulomb Interactions,” Proc. Natl. Acad. Sci. USA 103, 7560-7565 (2006).

J. C. Rodgers, C. Kaur, Y.-G. Chen and J. D. Weeks, “Attraction Between Like-Charged Walls: Short-Ranged Simulations Using Local Molecular Field Theory,” Phys. Rev. Lett. 97, 097801/1-4 (2006).

J. -D. Chai and J. D. Weeks, "Orbital-Free Density Functional Theory: Kinetic Potentials and Ab Initio Local Pseudopotentials", Phys. Rev. B 75, 205122/1-14 (2007).