Bio


Rodrigo's research focuses on the study of the thermodynamics and kinetics of materials, including extended defects in metals (such as dislocations, grain boundaries, and surface steps), kinetics of shock-compressed silica, and the chemistry of hydrocarbons. He employs a range of computational techniques in his research, including atomistic simulation methods (molecular dynamics and free-energy calculations), quantum mechanical calculations (density functional theory and path-integral/ring-polymer molecular dynamics), and machine learning tools.

Honors & Awards


  • Livermore Graduate Scholar, Materials Science Division, Lawrence Livermore National Laboratory (2015-2018)

Professional Education


  • Doctor of Philosophy, University of California Berkeley, Materials Science & Engineering (2018)
  • Master of Science, University of California Berkeley, Materials Science & Engineering (2015)
  • Master of Science, University of Campinas, Brazil, Physics (2013)
  • Bachelor of Science, University of Campinas, Brazil, Physics (2011)

All Publications


  • Transferable Kinetic Monte Carlo Models with Thousands of Reactions Learned from Molecular Dynamics Simulations. The journal of physical chemistry. A Chen, E., Yang, Q., Dufour-Decieux, V., Sing-Long, C. A., Freitas, R., Reed, E. J. 2019

    Abstract

    Molecular dynamics (MD) simulation of complex chemistry typically involves thousands of atoms propagating over millions of time steps, generating a wealth of data. Traditionally these data are used to calculate some aggregate properties of the system and then discarded, but we propose that these data can be reused to study related chemical systems. Using approximate chemical kinetic models and methods from statistical learning, we study hydrocarbon chemistries under extreme thermodynamic conditions. We discover that a single MD simulation can contain sufficient information about reactions and rates to predict the dynamics of related yet different chemical systems using kinetic Monte Carlo (KMC) simulation. Our learned KMC models identify thousands of reactions and run 4 orders of magnitude faster than MD. The transferability of these models suggests that we can viably reuse data from existing MD simulations to accelerate future simulation studies and reduce the number of new MD simulations required.

    View details for PubMedID 30735373

  • Quantum effects on dislocation motion from ring-polymer molecular dynamics NPJ COMPUTATIONAL MATERIALS Freitas, R., Asta, M., Bulatov, V. V. 2018; 4
  • Free energy of steps at faceted (111) solid-liquid interfaces in the Si-Al system calculated using capillary fluctuation method COMPUTATIONAL MATERIALS SCIENCE Saidi, P., Freitas, R., Frolov, T., Asta, M., Hoyt, J. J. 2017; 134: 184-189
  • Step free energies at faceted solid surfaces: Theory and atomistic calculations for steps on the Cu(111) surface PHYSICAL REVIEW B Freitas, R., Frolov, T., Asta, M. 2017; 95 (15)
  • Capillary fluctuations of surface steps: An atomistic simulation study for the model Cu(111) system Physical Review E Freitas, R., Frolov, T., Asta, M. 2017; 96 (4): 10
  • The Uhlenbeck-Ford model: Exact virial coefficients and application as a reference system in fluid-phase free-energy calculations JOURNAL OF CHEMICAL PHYSICS Leite, R. P., Freitas, R., Azevedo, R., de Koning, M. 2016; 145 (19)

    Abstract

    The Uhlenbeck-Ford (UF) model was originally proposed for the theoretical study of imperfect gases, given that all its virial coefficients can be evaluated exactly, in principle. Here, in addition to computing the previously unknown coefficients B11through B13, we assess its applicability as a reference system in fluid-phase free-energy calculations using molecular simulation techniques. Our results demonstrate that, although the UF model itself is too soft, appropriately scaled Uhlenbeck-Ford (sUF) models provide robust reference systems that allow accurate fluid-phase free-energy calculations without the need for an intermediate reference model. Indeed, in addition to the accuracy with which their free energies are known and their convenient scaling properties, the fluid is the only thermodynamically stable phase for a wide range of sUF models. This set of favorable properties may potentially put the sUF fluid-phase reference systems on par with the standard role that harmonic and Einstein solids play as reference systems for solid-phase free-energy calculations.

    View details for DOI 10.1063/1.4967775

    View details for Web of Science ID 000388956900005

    View details for PubMedID 27875891

  • Nonequilibrium free-energy calculation of solids using LAMMPS COMPUTATIONAL MATERIALS SCIENCE Freitas, R., Asta, M., de Koning, M. 2016; 112: 333-341