John E Klepeis

Group Leader, EOS & Materials Theory
Physics Division
Email: klepeis1@llnl.gov
Phone: +19254226103

Education

  • Ph.D., Applied Physics, Stanford University, 1989
  • M.S., Applied Physics, Stanford University, 1987
  • B.S., Applied and Engineering Physics, Cornell University, 1985

Research Interests

Development and application of first-principles all-electron density functional and semi-empirical tight-binding techniques to the electronic structure of surfaces and interfaces, semiconductors, f-electron materials, wide bandgap insulators, nanoparticles, intermetallic compounds, and materials at high pressure.  Equation of state of materials.

Honors and Awards

  • WPD Bronze Award for Bounding Pu Properties Team, 2019
  • Defense Programs Award of Excellence for LEP Replacement Material Team, 2018
  • Defense Programs Award of Excellence for Pu Aging Science Team, 2017
  • Defense Programs Award of Excellence for Modern Low-Z EOS Delivery Team, 2014
  • Defense Programs Award of Excellence for Multiphase EOS Team, 2010
  • Defense Programs Award of Excellence for Pit Lifetime Team, 2007
  • Outstanding Meeting Paper at the Materials Research Society Fall Meeting, 2006

Professional Background

John Klepeis is a theoretical and computational condensed matter physicist and Group Leader of the Equation of State (EOS) and Materials Theory Group in the Physics Division of the Physical and Life Sciences Directorate at LLNL, where he has been since 1989. He received his B.S. degree from the School of Applied and Engineering Physics at Cornell University in 1985. His graduate work was carried out in the Department of Applied Physics at Stanford University under Professor Walter A. Harrison. He obtained his M.S. degree in 1987 and his Ph.D. in 1989. At Stanford John studied Coulomb effects in semiconductor systems using self-consistent tight-binding electronic structure calculations. In particular, he applied this methodology to dopants in semiconductors, semiconductor heterojunctions, and metal-semiconductor interfaces. His thesis, entitled, Self-consistent electronic structure of semiconductor systems, shed light on the underlying principles that determine the valence band offset in heterojunctions and the Schottky barrier in metal-semiconductor contacts.

Upon graduation from Stanford in 1989 John accepted a post-doctoral position in the Condensed Matter Physics Division at LLNL. While at LLNL John has been a visiting scientist at the Fritz Haber Institute in Berlin, Germany with the group of Professor Mathias Scheffler for three months in the fall of 1991 and on three later occasions at the University of Erlangen-Nuremberg in Erlangen, Germany with the group of Professor Oleg Pankratov. At LLNL John has pursued the development and application of both first-principles all-electron density functional and semi-empirical tight-binding electronic structure techniques to a wide variety of condensed matter systems. Areas of interest have included the interpretation of experimental spectroscopic studies of surface, interface, and nanoparticle systems, the determination of the equation-of-state and thermodynamic properties of f-electron materials and the study of the elastic properties of materials as a function of pressure.  John has been the Group Leader of the EOS & Materials Theory Group since 2006.

Selected Publications

  1. A. Landa, P. Soderlind, I. I. Naumov, J. E. Klepeis, and L. Vitos, Kohn anomaly and phase stability in Group VB transition metals, Computation 6, 29 (2018).
  2. P. Soderlind, F. Zhou, A. Landa, and J. E. Klepeis, Phonon and magnetic structure in delta-plutonium from density-functional theory, Sci. Rep. 5, 15958 (2015).
  3. C. J. Wu, P. Soderlind, J. N. Glosli, and J. E. Klepeis, Shear-induced anisotropic plastic flow from body-centred-cubic tantalum before melting, Nature Materials 8, 223 (2009).
  4. P. Soderlind and J. E. Klepeis, First-principles elastic properties of alpha-Pu, Phys. Rev. B 79, 104110 (2009).
  5. R. E. Rudd and J. E. Klepeis, Multiphase improved Steinberg-Guinan model for vanadium, J. Appl. Phys 104, 093528 (2008).
  6. B. Lee, R. E. Rudd, J. E. Klepeis, P. Söderlind, and A. Landa Theoretical confirmation of a high-pressure rhombohedral phase in vanadium metal, Phys. Rev B 75, 180101(R) (2007).
  7. J. E. KlepeisIntroduction to first-principles electronic structure methods: Application to actinide materials, J. Mater. Res. 21, 2979 (2006).
  8. L. X. Benedict, J. E. Klepeis, and F. H. Streitz, Calculation of optical absorption in Al across the solid-to-liquid transition, Phys. Rev. B 71, 064103 (2005).
  9. H. Cynn, J. E. Klepeis, C.-S. Yoo, and D. A. Young, Osmium has the lowest experimentally determined compressibility, Phys. Rev. Lett. 88, 135701 (2002).
  10. J. E. Klepeis, O. Beckstein, O. Pankratov, and G. L. W. Hart, Chemical bonding, elasticity, and valence force field models: A case study for alpha-Pt2Si and PtSi, Phys. Rev. B 64, 155110 (2001).
  11. T. Wiell, J. E. Klepeis, P. Bennich, O. Björneholm, N. Wassdahl, and A. Nilsson, Local aspects of the adsorbate-substrate chemical bond in N/Cu(100) and O/Cu(100), Phys. Rev. B 58, 1655 (1998).
  12. A. K. McMahan and J. E. KlepeisDirect calculation of Slater-Koster parameters: Fourfold-coordinated silicon/boron phases, Phys. Rev. B 56, 12250 (1997).
  13. H. E. Lorenzana, J. E. Klepeis, M. J. Lipp, W. J. Evans, H. B. Radousky, and M. van Schilfgaarde, High-pressure phases of PbF2: A joint experimental and theoretical study, Phys. Rev. B 56, 543 (1997).
  14. J. E. Klepeis, K. J. Schafer, T. W. Barbee III, and M. Ross, Hydrogen-Helium mixtures at megabar pressures: Implications for Jupiter and Saturn, Science 254, 986 (1991).