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Interdisciplinary QC/CM Seminar | Can We Simulate the Quantum Dynamics of Many Electrons Both, Accurately and Fast?

Michael Bonitz (University of Kiel)
Thursday, October 21, 2021
2:00-3:00 PM
Off Campus Location
Join Zoom Meeting
Meeting ID: 940 9971 0193
Passcode: 761515

The accurate description of the ultrafast quantum dynamics of mutually interacting particles is of high interest in many areas of physics and chemistry. This includes the response of electrons in atoms, molecules, solids, and plasmas to short laser pulses. Similar phenomena occur in optical lattices where cold atoms are driven out of equilibium by ultrafast changes of the lattice parameters (quenches) [1]. A third example is the collective response of electrons in correlated 2D materials to the impact of charged particles [2]. Common to all these systems is that the interaction between the particles (i.e. correlations) significantly affects the time evolution. Common is also that for these systems a solution of the Schrödinger equation is impossible.

I will report how we approach the quantum dynamics of interacting particles. We apply the method of nonequilibrium Green functions (NEGF) which has proven to be a powerful tool to capture electron-electron correlations [3]. However, NEGF simulations are computationally expensive due to their cubic scaling with the simulation duration T. With the introduction of the generalized Kadanoff-Baym ansatz [4], quadratic scaling could be achieved for second order Born (SOA) selfenergies [5], which has substantially extended the scope of NEGF simulations. Recently [6], we could achieve linear scaling within SOA and even the GW and dynamically screened ladder approximations which is a break through for simulating the correlated electron dynamics.

[1] N. Schlünzen et al., Phys. Rev. B 93, 035107 (2016)
[2] K. Balzer et al., Phys. Rev. Lett. (2018)
[3] K. Balzer and M. Bonitz, Lect. Notes Phys. 867 (2013)
[4] P. Lipavský et al., Phys. Rev. B 34, 6933 (1986)
[5] S. Hermanns et al., Phys. Scripta T151, 014036 (2012)
[6] N. Schlünzen et al., Phys. Rev. Lett. 124, 076601 (2020); Joost
et al., Phys. Rev. B 101, 245101 (2020)
Building: Off Campus Location
Location: Virtual
Event Type: Workshop / Seminar
Tags: Physics, Science
Source: Happening @ Michigan from Department of Physics, Interdisciplinary QC/CM Seminars