Update theory authored by Philipp Rüssmann's avatar Philipp Rüssmann
......@@ -12,13 +12,13 @@ links:
Starting point: Schrödinger equation
```math
\mathcal{H}\|\psi\rangle = E\|\psi\rangle
\mathcal{H}|\psi\rangle = E|\psi\rangle
```
This can formally be written with the Green
function $`\mathcal{G}`$ as
```math
(\epsilon -\mathcal{H})\mathcal{G}(\epsilon)=1, \quad \epsilon=E+i\delta,
\quad \delta\>0
\quad \delta>0
```
Thus by knowing the GF one can extract the
systems properties, i.e. the expectation value $`\langle
......@@ -53,7 +53,7 @@ crystal into three steps: (i) compute the scattering properties of free
Lippmann-Schwinger equation, (ii) construct the multiple scattering via
the structural Green function from systems geometry and (iii) construct
the Green from the in (i) obtained wavefunctions and single-site
$`t$`-matrix and the in thep (ii) computed structural GF.
$`t`$-matrix and the in thep (ii) computed structural GF.
### (i) Single-site problem
......@@ -115,8 +115,8 @@ positions vanish, i.e. $`\Delta t=0`$. This allows us to embed the
impurity in a finite real space cluster into the host system. The
calculation is then done as follows.
- Compute the host systems Green function and write out the structural Green function as well as the single-site $`t`$ matrix of the host $`t_{\mathrm{host}}`$.
- From the impurity potential compute the $t$-matrix of the impurity and construct $`\Delta t=t_{\mathrm{host}}-t_{\mathrm{imp}}`$
- Solve the impurity Dyson equation: $`\underline{\underline{G}}=\underline{\underline{G}}_{\mathrm{host}}+\underline{\underline{G}}_{\mathrm{host}}\Delta t\underline{\underline{G}}`$
- Compute the new impurity potential from the Green function and update the input potential
- Repeat steps 2.-4. until the impurity potential converges
* Compute the host systems Green function and write out the structural Green function as well as the single-site $`t`$ matrix of the host $`t_{\mathrm{host}}`$.
* From the impurity potential compute the $`t`$-matrix of the impurity and construct $`\Delta t=t_{\mathrm{host}}-t_{\mathrm{imp}}`$
* Solve the impurity Dyson equation: $`\underline{\underline{G}}=\underline{\underline{G}}_{\mathrm{host}}+\underline{\underline{G}}_{\mathrm{host}}\Delta t\underline{\underline{G}}`$
* Compute the new impurity potential from the Green function and update the input potential
* Repeat steps 2.-4. until the impurity potential converges