Changes
Page history
Update theory (inline math $`x$` --> $x$ remove backticks)
authored
Jan 30, 2025
by
Johannes Wasmer
Show whitespace changes
Inline
Side-by-side
kkrsusc/theory.md
View page @
89d7b37b
...
...
@@ -17,28 +17,28 @@ function (KKR-GF) method, space is partitioned into nonoverlapping
regions surrounding the atoms, labeled $i$. These regions are taken as
spherical in the atomic sphere approximation (ASA), and the KS potential
is also assumed to be spherical around each atom,
$
`
V\^{\text{KS}}_i(r)$
`
, with $
`
r = |\vec{r}\,|$
`
and $
`
\hat{r} =
\vec{r}/r$
`
. Then the KS GF is expressed in terms of energy-dependent
$V
\^
{
\t
ext{KS}}_i(r)$, with $r = |
\v
ec{r}
\,
|$ and $
\h
at{r} =
\v
ec{r}/r$. Then the KS GF is expressed in terms of energy-dependent
scattering solutions for each atomic potential,
$
`
R_{i\ell}\^\sigma(r;E)\,Y_{L}(\hat{r})$
`
and
$
`
H_{i\ell}\^\sigma(r;E)\,Y_{L}(\hat{r})$
`
, which are products of
radial functions and (real) spherical harmonics, for each spin $
`
\sigma
= \;\uparrow,\,\downarrow$
`
and angular momentum $
`
L = (\ell,m)$
`
.
$
`
R_{i\ell}\^\sigma(r;E)$
`
is regular at the center of the ASA
sphere, and $
`
H_{i\ell}\^\sigma(r;E)$
`
diverges there.
$R_{i
\e
ll}
\^\s
igma(r;E)
\,
Y_{L}(
\h
at{r})$ and
$H_{i
\e
ll}
\^\s
igma(r;E)
\,
Y_{L}(
\h
at{r})$, which are products of
radial functions and (real) spherical harmonics, for each spin $
\s
igma
=
\;\u
parrow,
\,\d
ownarrow$ and angular momentum $L = (
\e
ll,m)$.
$R_{i
\e
ll}
\^\s
igma(r;E)$ is regular at the center of the ASA
sphere, and $H_{i
\e
ll}
\^\s
igma(r;E)$ diverges there.
The Korringa-Kohn-Rostoker Green function is given by
```
math
G_{ij}^\sigma(\vec{r}\,,\vec{r}\,';E) &=& \sum_{LL'}Y_L(\hat{r}) \big(\sqrt{E}\,R_{i\ell}^\sigma(r_<;E)\,H_{i\ell}^\sigma(r_>;E)\delta_{ij}\delta_{LL'} \nonumber\
&&\hspace{-4em} + R_{i\ell}^\sigma(r;E)\,G^{\sigma,\text{str}}_{iL,jL'}(E)\,R_{j\ell'}^\sigma(r';E)\big) Y_{L'}(\hat{r}') \; ,
```
where $
`
r_\< = \min(r,r\')$
`
and $
`
r_\> =
\max(r,r\')$
`
, and $
`
G\^{\sigma,\text{str}}_{iL,jL\'}(E)$
`
is the
where $r_
\<
=
\m
in(r,r
\'
)$ and $r_
\>
=
\m
ax(r,r
\'
)$, and $G
\^
{
\s
igma,
\t
ext{str}}_{iL,jL
\'
}(E)$ is the
structural GF, describing backscattering effects.
Near the Fermi energy ($
`
E_\text{F}$
`
) one may approximate
$
`
R_{i\ell}\^\sigma(r;E) \approx
R_{i\ell}\^\sigma(r;E_\text{F})$
`
.
Near the Fermi energy ($E_
\t
ext{F}$) one may approximate
$R_{i
\e
ll}
\^\s
igma(r;E)
\a
pprox
R_{i
\e
ll}
\^\s
igma(r;E_
\t
ext{F})$.
## Susceptibility
...
...
@@ -51,9 +51,9 @@ The transverse magnetic Kohn-Sham susceptibility is given by
& & \hspace{-6em}\Big(G_{ij}^{\bar\sigma}(\vec{r}\,,\vec{r}\,';E+\omega+\mathrm{i} 0)\,\text{Im}\,G_{ji}^{\sigma}(\vec{r}\,',\vec{r}\,;E) + \text{Im}\,G_{ij}^{\bar\sigma}(\vec{r}\,,\vec{r}\,';E)\,G_{ji}^{\sigma}(\vec{r}\,',\vec{r}\,;E-\omega-\mathrm{i} 0)\Big) \, .
```
Here, $
`
\chi\^{\uparrow\downarrow}$
`
and
$
`
\chi\^{\downarrow\uparrow}$
`
correspond to $
`
\chi\^{+-}$
`
and
$
`
\chi\^{-+}$
`
, respectively.
Here, $
\c
hi
\^
{
\u
parrow
\d
ownarrow}$ and
$
\c
hi
\^
{
\d
ownarrow
\u
parrow}$ correspond to $
\c
hi
\^
{+-}$ and
$
\c
hi
\^
{-+}$, respectively.
### Dyson-like equation
...
...
...
...