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My PhD thesis - Condensed Matter Theory - Imperial College London

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CHAPTER 8. APPLYING THE PLASMON NORMAL MODE THEORY TO<br />

SLAB SYSTEMS<br />

0.06<br />

LDA<br />

short-range Jastrow<br />

n(z)<br />

0.04<br />

0.02<br />

0<br />

0 s<br />

z<br />

Figure 8.18: The electron density profile for a Jastrow factor consisting of only the short-range<br />

two-body function u cusp and the corresponding one-body term χ cusp .<br />

than having the precise form of u. Up to this point, no optimisation has been carried<br />

out: all parameters have been calculated in advance, based only on theoretical<br />

considerations. To improve the plasmon Jastrow factor, a reasonable approach is<br />

to take the wave function of equation (8.121) as a starting point, and then to add<br />

a small one-body term with adjustable parameters, with the aim of restoring the<br />

initial density.<br />

8.4.2 Bounded slab<br />

Although the plasmon Jastrow factor for the unbounded slab performed well, and<br />

should provide a good starting point for optimisation, the unoptimised form did not<br />

improve on the simple short-ranged Jastrow factor, which came closer to maintaining<br />

the LDA density and hence generated a lower energy.<br />

The bounded jellium slab is in some ways a more accurate representation of<br />

160

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