Fysiikan tutkimusseminaari: Professori Artur Tamm (Tarton yliopisto, Viro)

Tervetuloa professori Artur Tammin tutkimusseminaariin!

Large-Scale Atomistic Simulations of Non-Equilibrium Processes Driven by Electron-Ion Interactions: Case Study of Laser Heated Tungsten

Abstract: 

Metallic systems can be excited to a non-equilibrium state by applying laser radiation on the sample. The hot electrons will start to heat the cold lattice through the electron-ion interaction. The effect of the interaction is the different excitation rates for different phonon modes, where short-wavelength modes are excited faster than long-wavelength modes. Furthermore, the dynamics is complicated even more with the addition of phonon-phonon scattering, which acts as an additional channel for redistributing energy in the lattice while it evolves towards equilibrium. Recent experimental measurements capture this intricate dynamics with excellent temporal and spatial resolution. Capturing these processes with atomistic molecular dynamics requires introduction of electron-ion coupling. We have developed a Langevin dynamics based approach that captures the electron-ion interaction as observed in time-dependent density functional theory calculations. We will present our simulation results of the non-equilibrium dynamics in W excited by a laser pulse. Also, we will show the importance of both electron-ion coupling as well as phonon-phonon scattering in this process. Finally, we will demonstrate some additional processes that our model could handle.

Bio: 

Artur Tamm did his PhD degree in the University of Tartu in Estonia. After that he did a postdoc in Uppsala University and later transitioned to LLNL. He became a staff scientist at the LLNL after completing his postdoc. Now he is an associate professor at the University of Tartu. Artur has been working with methods ranging from potential development, molecular dynamics and density functional theory. His main interests are in model development on topics related to non-equilibrium dynamics, such as radiation damage, laser-matter excitation, compression shockwaves, ultrafast melting.

Host: Prof. Andrea Sand