Frank Graziani, Paul Grabowski, John Castor, Jim Glosli, Mike Surh, Lorin Benedict, Christian Scullard, Alfredo Correa, Dave Richards, Heather Whitley, Ronnie Shepherd, Stefan Hau-Reige, Richard London, Bruce Langdon, Joe Bauer (LLNL)

Collaborators:

Aurora Pribram-Jones (UC Merced),

Liam Stanton (San Jose State),

Michael Murillo (Michigan State University)

Michael Desjarlais (SNL)

Andreas Markmann, Victor Batista (Yale)

The Cimarron project is a multi-institution collaboration dedicated to the prediction and measurement of properties of dense, highly collisional, and strongly-coupled plasmas. The main workhorse of the project is the ddcmd code, a domain-decomposition massively parallel classical molecular dynamics code capable of handling long-range forces such as Coulomb interactions. Phenomena studied are those associated with fusion and thermonuclear burn: electron-ion temperature equilibration, alpha-particle stopping power, electrical and thermal conductivities, etc. These phenomena have been traditionally studied with theoretical approaches such as classical and quantum kinetic theory, and computational approaches such as particle-in-cell (PIC) simulations and traditional radiation hydrodynamics codes. What ddcmd provides is a particle-based approach in which various Coulomb scattering cross-sections are computed in the course of the simulation, rather than input (as in PIC and rad-hydro methods). The cost of this, besides increased computational rigor, is the need to use statistical potentials rather then pure-Coulomb, to

- handle the effects of quantum diffraction (crucial to include for plasmas in the fusion-burning regime), and
- to prevent electron-ion collapse which would force a classical simulation of oppositely-charged particles to become unstable.

Current areas of active research include: The study of the efficacy of various forms of statistical potentials in mimicking the quantum/pure-Coulomb answers at weak coupling (where various time-dependent properties are sufficiently well-known), the treatment of time-evolving bound states in H or DT plasmas with high-Z dopants, matter-radiation coupling at extreme conditions, and advanced multi-step integration methods to handle disparate time-scales in the MD simulations. See Ref. 4 below for an overview of the entire scope of the Cimarron project.

A simulation of electron-ion temperature equilibration in hydrogen. (See Ref. 8 below.)

### Recent Publications

- Christian R. Scullard, Susana Serna, Lorin X. Benedict, C. Leland Ellison, and Frank R. Graziani, “Analytic expressions for electron-ion temperature equilibration rates from the Lenard-Balescu equation”,
*Phys. Rev. E*97, 013205 (2018). - Lorin X. Benedict, Michael P. Surh, Liam G. Stanton, Christian R. Scullard, Alfredo A. Correa, John I. Castor, Frank R. Graziani, Lee A. Collins, Ondrej Certik, Joel D. Kress, and Michael S. Murillo, "Molecular dynamics studies of electron-ion temperature equilibration in hydrogen plasmas within the coupled-mode regime", by
*Phys. Rev. E*95 043202 (2017)." - Michael P. Desjarlais, Christian R. Scullard, Lorin X. Benedict, Heather D. Whitley, and Ronald Redmer, "Density-functional calculations of transport properties in the non-degenerate limit and the role of electron-electron scattering",
*Phys. Rev. E*95, 033203 (2017). - Heather D. Whitley, David M. Sanchez, Sebastien Hamel, Alfredo A. Correa, and Lorin X. Benedict, Molecular dynamics simulations of warm dense carbon
**55**, 390 (2015) - Heather D. Whitley, Christian R. Scullard, Lorin X. Benedict, John I. Castor, Amanda Randles, James N. Glosli, David F. Richards, Michael P. Desjarlais, and Frank R. Graziani, Lenard-Balescu calculations and classical molecular dynamics simulations of electrical and thermal conductivities of hydrogen plasmas , Contrib. Plasma Phys.
**55**, 192 (2015). - Lorin X. Benedict, Michael P. Surh, John I. Castor, Saad A. Khairallah, Heather D. Whitley, David F. Richards, James N. Glosli, Michael S. Murillo, Christian R. Scullard, Paul Grabowski, David Michta and Frank R. Graziani, Molecular dynamics simulations and generalized Lenard-Balescu calculations of electron-ion temperature equilibration in plasmas, Phys. Rev. E
**86**, 046406 (2012). - Frank R. Graziani, Victor S. Batista, Lorin X. Benedict , John I. Castor, Hui Chen, Sophia N. Chen, Chris A. Fichtl, James N. Glosli, Paul E. Grabowski, Alexander T. Graf, Stefan P. Hau-Riege, Andrew U. Hazi, Saad A. Khairallah, Liam Krauss, A. Bruce Langdon, Richard A. London, Andreas Markmann, Michael S. Murillo, David F. Richards, Howard A. Scott, Ronnie Shepherd, Liam G. Stanton, Michael P. Surh, Jon C. Weisheit, Heather D. Whitley, Large-scale molecular dynamics of dense plasmas: the Cimarron project High Energy Density Physics
**8**, 105 (2012). - Lorin X. Benedict, James N. Glosli, David F. Richards, Frederick H. Streitz, Stefan P. Hau-Riege, Frank R. Graziani, Michael S. Murillo, and John F. Benage, Molecular dynamics simulations of electron-ion temperature equilibration in an SF_6 plasma, Phys. Rev. Lett.
**102**, 205004 (2009). - James N. Glosli, Frank R. Graziani, Richard M. More, Michael S. Murillo, Frederick H. Streitz, Michael P. Surh, Lorin X. Benedict, Stefan Hau-Riege, A. Bruce Langdon, and Richard A. London, Molecular dynamics simulations of temperature equilibration in dense hydrogen, Phys. Rev. E
**78**, 025401(R) (2008).