QCM-2013-3-0007 Performance of Time Dependent Density Functional Theory in the strong field photoionisation of noble gas atoms

Application Id: QCM-2013-3-0007

1.- Activity Title:
Performance of Time Dependent Density Functional Theory in the strong field photoionisation of noble gas atoms
Area: Chemistry and Materials Science and Technology

2.- Results of this activity from the previous application periods

a) Description of the results obtained during the previous periods
The main idea behind this project is to test the performance of Time Dependent Density Functional Theory (TDDFT) in the strong high intensity regime for two noble gas atoms, Neon and Argon (we still have not tested Xenon because we are still testing Argon), with respect to the lowest order non vanishing perturbation theory (LOPT) results that have been obtained previously. In order to do this, I have used their same parameters and I have performed the calculations with the Octopus code. In particular I have compared the number of ejected electrons obtained from both methods. In order to simulate our systems I have placed them inside a box with a certain dimension limiting our systems in space. A limited box in space leads to reflections of the outgoing electrons bouncing back to the system which is unphysical. Therefore a relatively big box is necessary to converge our calculations. For Neon we have seen that our TDDFT results are good but this hasn't been the case for Argon, which is why we want to extend our application period. For Argon apart from the tests that I have performed mentioned below in the Research Project Description area, we have performed other tests to understand why this was the case and that is why all the assigned Marenostrum hours for this period have already been used. Note that as explained below, for each new pseudopotential, absorbing boundary method tested ... we have to test two pulse lengths per atom, 7 intensities per functional and 8 different functionals... which leads to many calculations.

From our calculations, we have reached the following conclusions:

Argon is stabler than Neon in time with respect to the ejection of electrons.

I have computed the cross sections and compared them to the experimental ones to show that for both Ne and Ar we need a box of 30 atomic units to avoid unphysical reflections. For both cases the theoretical cross section underestimates the experimental one. Therefore we cannot understand why we get better results for Neon than for Argon from the cross sections.

The results hardly change if I use different absorbing methods but they do improve if we use the 105eV
laser pulse and they particularly improve if we use a harder pseudopotential. This might be why we
obtain better results for Neon, as for Neon we use a 93eV laser and it is more strongly bound because of its size, so that the number of escaped electrons is smaller than for Argon. Therefore for Argon we
either need a harder two inner core and eight semi inner core pseudopotential or a softer two inner
core only pseudopotential which is tougher computationally because more memory is required.

As the pseudopotential becomes harder, the ground state eigenvalues tend towards the all-electron eigenvalue limit. We are testing the transferability of the pseudopotential, because the pseudopotentials have been generated for the neutral configuration.

If the electrons do not interact, the results get worse, so that the electron interaction effects are not negligible.

To summarise, we want to test now the effect of the two new different pseudopotentials: a harder two inner core and eight semi inner core pseudopotential AND a softer two inner
core only pseudopotential. We want to test them using a box size of 30 atomic units (because we avoid box states by doing so) and these require a very small spacing to achieve convergence.
For each pseudopotential, note that we want two pulse lengths per atom, 7 intensities per functional and 8 different functionals. I would also like to install a new octopus version which outputs the ionisation channels. This would be useful to compare how the LOPT ones compare to our TDDFT ones. This option can be added when I submit my calculations, but due to this new extra feature which has to be outputted, the calculations will also take longer.

b) List of publications, communications in conferences, presentations, patents, etc, resulted in previous periods of this Activity
The results about Neon and Argon from the first period and this second one will be published as soon as the calculations provide us with a better physical understanding. The title we have in mind for this publication is the following:

Application of time-dependent density-functional theory in strong-field ionization of Neon and Argon

After that, in another application period, we also plan to perform the same analysis for Xenon, which we will also try to publish.

3.- Research Project Description:

e) Specific Activity proposed:
To perform our calculations we are using the Octopus code [http://www.tddft.org/programs/octopus/wiki/index.php/Main_Page] which is already installed in MareNostrum. We need to perform many calculations, as we need to test the laser parameters, the TDDFT density functionals, as well as noble gas atoms from an all-electron and pseudopotential calculation as I mentioned in section c) to have a clear idea of how TDDFT works in the strong field photoionisation regime.

In our case, we have to test many calculations and each one of the pseudopotential calculations. On the other hand, we also have to consider that these calculations will take longer for noble gas atoms with more electrons. I also want to output the ionisation channels.

To concretise, we have to test two noble gas atoms (maybe Xenon later on but we still want to understand Argon), one pulse frequency (we stick to 93eV for Neon and 105eV for Argon), two pulse lengths per atom, 7 intensities per functional and 8 different functionals (the 4 functionals mentioned above from a pseudopotential calculation) per atom. Right now, my priority to run calculations is very low because I've used all my hours for this period. I'm having memory problems to run the calculations on Marenostrum but I hope it is possible to fix this. Taking all this into account I would need largest long run job calculations only, I would need to submit 112 calculations, which will take on average 45 hours using 80 processors. This has been calculated taking into account how long the calculations lasted using a softer pseudopotential.

f) Computational algorithms and codes outline:
The project involves the use of an installed computer code in MareNostrum that implements techniques of TDDFT in real-space. We want to use the Octopus code (http://www.tddft.org/programs/octopus/wiki/index.php/Main_Page) written by M. Marques et al. This is a real-time, real-space TDDFT code.
The code is parallelised in spatial domains, states and k-points. It uses the libraries FFTW3, LAPACK/BLAS, GSL, Perl, NetCDF.
This code has been tested with excellent performances on MareNostrum in previous projects carried out by our group.

4.- Software and Numerical Libraries

Software components that the project team requires for the activity
Applications + Libraries:
Compilers and Development Tools:
Utilities + Parallell Debuggers and Performance Analysis Tools:
Other requested software: Please install the latest trunk version of the OCTOPUS code, because the ionisation channels option has been implemented recently.
Propietary software:

5.- Research Team Description
a) name of Team Leader: Angel Rubio Secades
Institution: Departamento de Física de Materiales, Facultad de Químicas, Universidad del Pais Vasco
e-mail: angel [dot] rubio [at] ehu [dot] es
Phone: +34-943018292

Curriculum Vitae of the Team Leader:
Angel Rubio is a Professor of Condensed Matter Physics in the Department of Materials of the Faculty of Chemistry in the Basque Country University (UPV/EHU). His research activity is internationally recognized and he has received numerous honors and awards. Among them, we would like to mention: National Prize for the best Spanish undergraduate student of Physics (1989), the Royal Spanish Physical Society Prize "Outstanding young researchers" (1992); the Sir Allan Sewell Fellowship School of Science, Griffith University, Australia (2004); the Fellow of the American Physical Society: Materials Science Division (2004); The 2005 Friedrich Wilhelm Bessel Research Award, Humboldt Foundation, Germany (2005); DuPond Prize on Science, (2006); ther “Distinguished Visiting Scientist”, Fritz Haber Institute der Max-Planck- Gesellschaft, Berlin (2009); The Outstanding Referee award, American Physical Society, (2009).
Prof. Rubio has an outstanding publication record: more than 200 scientific publications with more than 13000 citations (Hirsch index 57). His group has a deep and long-standing experience in code-development (octopus, Yambo, Abinit) and usage of high-performance computing facilities. The main research activity is in the field of theory and modeling of electronic and structural properties developing novel theoretical tools and computational codes to investigate the electronic response of solids, nanostructures to external electromagnetic fields. The group is involved in the organisation of the International Workshop and School: Time-Dependent Density-Functional Theory: Prospects and Applications, held every two years in Benasque Center for Science, Benasque, Spain. The group also collaborates with MareNostrum for developing and testing high-performance codes.

d) Names of other researchers involved in this activity:
1) Alison Crawford Uranga
Institution: Nano-Bio Spectroscopy group and ETSF Scientific Development Center, Departamento de Física de Materiales, Centro de Física de Materiales CSIC-MPC and DIPC, Universidad del País Vasco UPV/EHU, Avenida de Tolosa 72, E-20018, San Sebastián, Spain
E-mail: alisonc1986 [at] gmail [dot] com

2) Esa Räsänen
Institution: Department of Physics, Tampere University of Technology, FI-33101 Tampere, Finland
E-mail: esa [dot] rasanen [at] tut [dot] fi

3) Umberto De Giovannini
Institution: Nano-Bio Spectroscopy group and ETSF Scientific Development Center, Departamento de Física de Materiales, Centro de Física de Materiales CSIC-MPC and DIPC, Universidad del País Vasco UPV/EHU, Avenida de Tolosa 72, E-20018, San Sebastián, Spain
E-mail: umberto [dot] degiovannini [at] ehu [dot] es

4) Micael J. T. Oliveira
Institution: Center for Computational Physics, University of Coimbra, Rua Larga, 3004-516 Coimbra, Portugal
E-mail: micael [at] teor [dot] fis [dot] uc [dot] pt

5) Peter Lambropoulous
Institution: Institute of Electronic Structure and Laser
Foundation for Research and Technology
P.O. Box 1527, GR-71110, Heraklion, Greece
E-mail: labro [at] iesl [dot] forth [dot] gr

6) Stefan Kurth
Institution: Nano-Bio Spectroscopy group and ETSF Scientific Development Center, Departamento de Física de Materiales, Centro de Física de Materiales CSIC-MPC and DIPC, Universidad del País Vasco UPV/EHU, Avenida de Tolosa 72, E-20018, San Sebastián, Spain
E-mail: stefan_kurth [at] ehu [dot] es

e) The five most relevant publications, in the last five years, from the members of the research team:
Octopus: a tool for the application of time-dependent density functional theory A. Castro, H. Appel, Micael Oliveira, C.A. Rozzi, X. Andrade, F. Lorenzen, M.A.L. Marques, E.K.U. Gross, and A. Rubio,, Phys. Stat. Sol. B 243 2465-2488 (2006)

Ab-initio angle and energy resolved photoelectron spectroscopy with time-dependent density-functional theory, U. De Giovannini, D. Varsano, M. A. L. Marques, H. Appel, E. K. U. Gross, A. Rubio Physical Review A 85, 062515 (2012)

Strong-field ionization suppression by light field control, Esa Räsänen and Lars Bojer Madsen, Phys. Rev. A 86, 033426 (2012)

Simulating pump-probe photo-electron and absorption spectroscopy on the attosecond time-scale with time-dependent density-functional theory, U. De Giovannini, G. Brunetto, A. Castro, J. Walkenhorst, A. Rubio Chemphyschem 14, 1363 - 1376 (2013)

Route to direct multiphoton multiple ionisation, P. Lambropoulos et al., Phys. Rev. A, 83, 021407(R), 2011

f) Does any of the researchers involved in the activity apply to the mobility program?: No

6.- Resources
a) Estimated resources required for the Activity fot the current Application Period:

Requested machine: MareNostrum 3 (IBM System X iDataplex with Infiniband / >40000 cores)
Interprocess communication Tighltly Coupled

Typical job run:
Number of processors needed for each job 0.00
Estimated number of jobs to submit 0.00
Average job durations (hours) per job 0.00
Total memory used by the job (GBytes) 0.00

Largest job run:
Number of processors needed for each job 80.00
Estimated number of jobs to submit 112.00
Average job durations (hours) per job 45.00
Total memory used by the job (GBytes) 150.00

Total disk space (Gigabytes) Minimun 250.00 Desirable 300.00
Total scratch space (Gigabytes) Minimun 50.00 Desirable 100.00
Total tape space (Gigabytes) Minimun 50.00 Desirable 100.00

Total Requested time: (Thousands of hours) 404.00

INFORMATION: The estimated cost of the requested hours, considering only the electricity cost, is 4617.72 euros.

The required resources have to be executed in the selected machines, the other architectures do not fit the requirements to execute the proposal.
** this option implies that if no hours in this machine/these machines are available, the acces committee will reject the full application.