"We describe the work performed during the active period:
- During the 0-3 months, the MC researcher settled in Universidad de Salamanca and performed the introductory tasks mentioned in Work Plan 1 (WP1). The theory for later implementing the time-dependent core-hole dynamics was published in [1].
- In the five following months, 3-8 months, we started to implement the code that calculates the electronic structure of any molecule, needed for WP2 and WP3. We choose to build the time-dependent code on the top of a Gaussian basis library that allowed calculating all electronic structure of any molecule. Then we develop a scattering code to calculate the continuum orbitals for photoelectrons and Auger electrons (WP3).
- During the 8-11 months period, we started to implement the time-dependent program to calculate the molecular core-hole dynamics (WP3). We choose to implement the equations published in [1] with a four-order Runge-Kutta to evolve the quantum system, parallelized with Open MP libraries. The program has been initially designed to simulate both excitation and ionization of the x-ray pulse, and the following Auger decay via electron correlations. Also, we could simulate the nuclear propagation, but this has not been tested. This new code allowed us investigating the charge migration in the dication molecular ion. In Figure 1 we show the coherent electron transfer calculated for FC2H. An x-ray pulse ionizes the 1s electron from the F atom, and after Auger decay, a two-hole distribution is created in the valence shell. When we solve the dynamics, accounting for all possible interferences between different Auger channels, we observe a coherent oscillation (blue line), in contrast to a standard exponential incoherent decay (red line). We noticed that the coherent oscillation produce a clear electron transfer across the molecule, Fig 1b. Our results are submitted for publication [3].
Also, we adopt our code to simulate the dynamics in two-dimensional materials. In Figure 2 we show the calculate HHG spectrum from graphene interacting with a 3-cycle 3mm-wavelength pulse, with two different intensities. We submitted our results to New J. Phys. [2].
- During the last two months, 11-14 months, we have been working in connecting the SFA code of the host group with the code that simulates the core-hole molecular dynamics. First we tested with hydrogen molecular ion, in which we can obtain an exact solution and make a quantitative comparison with the SFA model. First results are promising and we will continue working in this line.
References:
[1] A. Picón, ""Time-dependent Schrödinger equation for molecular core-hole dynamics"", Phys. Rev. A 95, 023401 (2017).
[2] O. Zurrón, A. Picón, and L. Plaja, ""Theory of high-order harmonic generation for gapless graphene"", accepted in New J. Phys.
[3] A. Picón, C. Bostedt, C. Hernández-García, and L. Plaja, ""Auger-induced charge migration"", submitted to PRX.
Dissemination:
- RSEF +Física, Universidad de Salamanca, Spain 27 November 2017. Outreach talk.
- USTS 2017 - Ultrafast Science & Technology Spain, Salamanca, Spain 22-24 November 2017. Oral conference.
- XXXVI Reunión Bienal de la Real Sociedad Española de Física, Santiago de Compostela, Spain 17-21 July 2017. Oral conference.
- CLEO - ECEQ European Quantum Electronics Conference, Munich, Germany 25-29 June 2017. Oral conference.
- SPIE Optics + Optoelectronics, Prague, Czech Republic 24-27 April 2017. Oral conference.
- IWP-RIXS-2017 ""International workshop of photoionization and resonant inelastic x-ray scattering"", Aussois, France 26-31 March 2017. Oral conference."
