PhD Defense: Non-adiabatic processes in the radiation damage of materials from first principles
CFM Seminars
- Speaker
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Rafi Ullah (nanoGUNE)
- When
-
2018/03/23
11:00 - Place
- CFM Auditorium
- Add to calendar
-
iCal
Ions shooting through solids produce damage of different kinds depending on
the kind of projectile, its velocity and the kind of material. This damage can
be of great importance in several contexts:in the nuclear industry (nuclear
fuels, materials for hosting nuclear waste, structural materials in reactor
chambers), in the electronics industry (the smaller a device the more
sensitive to cosmic rays, especially in the space and aeronautics industries),
and in ion radiotherapy of cancer, to name the most prominent. In all of these
contexts it is important to be able to understand, control and predict the
amount and character of the damage undergone by the relevant materials under
the expected radiation. There are active research lines in radiation damage in
all these contexts, which consider the damage under varied approximations.
In classical molecular dynamics simulations of the damage, the quantum
mechanical dynamic response of the host electrons is completely ignored. The
ion (projectile)-energy loss to the host electrons, characterized as
electronic stopping power (ESP), is the most dominant dissipative mechanism
over most of the projectile velocities. The ESP is one of the primary
ingredients that dictates the early stages of damage.
A multitude of approximate models have been developed and applied to this
problem since the early years of quantum physics. Following the pioneering
work of Fermi and Teller [1], Lindhard in 1954 [2] and Ritchie in 1959 [3],
applied a linear response formalism to study the energy loss in simple metals.
In 1976, Almbladh et al. [4], and from 1981 onward Echenique et al. [5] have
used density functional theory (DFT) to calculate the nonlinear response of
the electron gas to the perturbation produced by a swift ion. Ever since the
problem has been extensively studied using various approaches [6]. We have
applied real-time time-dependent density functional (RT-TDDFT) formalism [7]
to compute the ESP in different materials [8, 9].
[1] E. Fermi and E. Teller, Phys. Rev. 72, 399 (1947).
[2] J. Lindhard, Dan. Mat. Fys. Medd. 28 (1954).
[3] R. H. Ritchie, Phys. Rev. 114, 644 (1959).
[4] C. O. Almbladh, U. von Barth, Z. D. Popovic, and M. J. Stott, Phys. Rev. B
14, 2250 (1976).
[5] P. Echenique, R. Nieminen, and R. Ritchie, Solid State Commun. 37, 779
(1981).
[6] C. P. Race, D. R. Mason, M. W. Finnis, W. M. C. Foulkes, A. P. Horseld,
and A. P. Sutton, Rep. Prog. Phys. 73, 116501 (2010).
[7] R. Ullah, A. Garaizar, F. Corsetti, D. S_x0013_anchez-Portal, J. Kohano, and E.
Artacho, Comput. Phys. Commun. (in preparation) (2018).
[8] R. Ullah, F. Corsetti, D. S_x0013_anchez-Portal, and E. Artacho, Phys. Rev. B
91, 125203 (2015).
[9] R. Ullah, E. Artacho, and A. A. Correa, Phys. Rev. Lett. (submitted)
(2018).
**Supervisor** : E. Artacho