Das Pemmaraju

Stanford Institute for Materials and Energy Sciences,
SLAC National Accelerator Laboratory, Menlo Park, CA-94025, USA

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Abstract

Advances in ultrafast laser spectroscopies over the last two decades have led to the development of a wide variety of experimental protocols for detailed time-domain investigations of electron dynamics in materials. Laser pulses across a wide range of intensities are now routinely deployed to drive valence- and core-level excitations that control and probe electron dynamics on femtosecond to attosecond timescales [1]. In this context, theoretical methods going beyond a perturbative treatment of light-matter interaction are increasingly relevant for guiding experimental efforts and aiding the interpretation of complex time-resolved and/or nonlinear spectroscopies. In solid-state systems, the velocity-gauge formulation of real-time TDDFT (VG-RT-TDDFT) [2,3] has emerged as an efficient first-principles approach for describing laser-matter interactions and has been utilized within the past decade to model a number of strong-field phenomena [2,4]. I will discuss the formal framework of VG-RT-TDDFT within Kohn-Sham theory and describe recent efforts to extend this versatile approach to generalized Kohn-Sham (GKS) [5] theory for a unified description of valence and core electron dynamics in crystalline solids [6]. In particular, accuracy improvements afforded by GKS theory for the description of important solid-state excitonic
effects in the time-domain will be discussed [6]. Within this methodology, the calculation of observables relevant to time-resolved and/or nonlinear spectroscopies employing laser frequencies from the infrared to soft X-ray range will also be illustrated.

Key References

[1] P. M. Kraus, M. Zürch, S. K. Cushing, D. M. Neumark, and S. R. Leone, Nat. Rev. Chem. 2, 82 (2018).
[2] K. Yabana, T. Sugiyama, Y. Shinohara, T. Otobe, and G. F. Bertsch, Phys. Rev. B 85, 045134 (2012).
https://salmon-tddft.jp/
[3] C. D. Pemmaraju, F. D. D. Vila, J. J. J. Kas, S. A. A. Sato, J. J. J. Rehr, K. Yabana, and D. Prendergast, Comput.
Phys. Commun. 226, 30 (2018).
[4] K. Krieger, J. K. Dewhurst, P. Elliott, S. Sharma, and E. K. U. Gross, J. Chem. Theory Comput. 11, 4870
(2015).
[5] R. Baer and L. Kronik, Eur. Phys. J. B 91, 170 (2018).
[6] C. D. Pemmaraju, Comput. Condens. Matter 18, e00348 (2019).