A few applications of Density Functional Theory:
materials modelling ab-initio
Julie Staunton
Department of Physics, University of Warwick, U.K.
Midlands Alliance in Research Computing (MARC)
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Electrons in DNA.
E.Artacho et al., MOLECULAR PHYSICS, 101, 1587, (2003)
Surface of constant electron density of a DNA molecule . It has eleven
base pairs (715 atoms) repeated periodically. The colour represents the
selfconsistent electrostatic potential obtained from the density functional
calculation. Red corresponds to negative regions (oxygen and nitrogen) and
blue to positive ones (hydrogen).
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Figure from article by M.Coey and S.Sanvito, Physics World 17,(11), 34, (Nov. 2004).
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Magnetic order in the Heavy Rare Earths
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Magnetic phase diagram of heavy rare earths
Lanthanide Contraction and Magnetism in the Rare Earth Elements, (Hughes et al, Nature, 446, 650, (2007))
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High density magnetic recording
Superparamagnetic limit r0 =
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kB T 1
( Ku ) 3
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Co/Cox F e1−x nanoclusters on P t (1,1,1).
Rusponi et al. Nature Materials 2, 546 (2003); Honolka et al. Phys.Rev.Lett. 102, 067207, (2009).
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45
Co discs
Fe discs
Co discs + 1xFe rim
Co discs + 2xFe rim
40
35
MAE (meV)
30
25
20
15
10
5
0
1
7
19
37
61
91
127
number of cluster atoms
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Write limitations · · · Thermally Assisted Recording (TAR)
Potential high density magnetic recording media: iron-platinum alloys.
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Magnetic anisotropy energy (meV)
0
MCA FePt
−0.5
<−−model
−1
−1.5
−2
0
0.2
0.4
0.6
0.8
1
Magnetisation squared
Temperature dependence of magnetic structure of FePt
J.B.Staunton et al.,Phys.Rev.Lett. 93, 257204, (2004)
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Heterogeneous magnetic systems
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Summary and Forward Look
• Density Functional Theory basis for ab-initio modelling of materials.
Emphasis on describing the electron ‘glue’. Heavy exploitation of HPC.
Many applications, e.g.
• Disparate materials in atomic contact. Physics at and across interfaces.
– Different local order parameters. E.g FM/AFM; metal/insulator;
RE/TM; SC/magnet, FM/piezoelectric · · ·
– Rich physics. Frustration effects, disorder, dimensionality, interface
roughness, nanocluster size · · ·
Coupling between different phenomena.
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