Formula Report

Source: /home/wkolbe/pdfdrill-library/kolbe2018hubbard/kolbe2018hubbard.lines.json  |  MathExpressions: 238  |  Equations: 61

Inline Math — MathExpression tiddlers (238)

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kolbe2018hubbard_FO0001N=10
kolbe2018hubbard_FO0002j=(1,10)
kolbe2018hubbard_FO0003j=(1, N)
kolbe2018hubbard_FO0004N=6
kolbe2018hubbard_FO0005t^{\prime}=0.5
kolbe2018hubbard_FO0006U=1
kolbe2018hubbard_FO0007J
kolbe2018hubbard_FO0008J \rightarrow 0
kolbe2018hubbard_FO0009J \rightarrow \infty
kolbe2018hubbard_FO0010j=1
kolbe2018hubbard_FO0011j=N-1
kolbe2018hubbard_FO0012N
kolbe2018hubbard_FO0013U>t
kolbe2018hubbard_FO0014\mathcal{H}
kolbe2018hubbard_FO0015\mathbb{C}^{n}
kolbe2018hubbard_FO0016|\chi\rangle,|\phi\rangle,|\psi\rangle \in \mathcal{H}
kolbe2018hubbard_FO0017c, d
kolbe2018hubbard_FO0018|0\rangle+|\phi\rangle=|\phi\rangle
kolbe2018hubbard_FO0019|0\rangle \in \mathcal{H}
kolbe2018hubbard_FO0020|\phi\rangle+|\psi\rangle, c|\psi\rangle
kolbe2018hubbard_FO0021\mathcal{H} \times \mathcal{H} \rightarrow \mathbb{C}^{n}
kolbe2018hubbard_FO0022\mathcal{H}^{*}
kolbe2018hubbard_FO0023\langle\psi, \phi\rangle=\langle\psi \mid \phi\rangle: \mathcal{H} \times \mathcal{H}^{*} \rightarrow \mathbb{C}^{n}
kolbe2018hubbard_FO0024\langle\psi| \in \mathcal{H}^{*}
kolbe2018hubbard_FO0025\langle\psi|
kolbe2018hubbard_FO0026|\psi\rangle
kolbe2018hubbard_FO0027a, b
kolbe2018hubbard_FO0028\phi, \psi \in \mathcal{H}
kolbe2018hubbard_FO0029\hat{\mathrm{A}}
kolbe2018hubbard_FO0030\hat{\mathrm{A}}(a \cdot \psi+b \cdot \phi)=a \cdot \hat{\mathrm{~A}} \psi+b \cdot \hat{\mathrm{~A}} \phi
kolbe2018hubbard_FO0031\hat{\mathrm{A}}(a \cdot \psi+b \cdot \phi)=a^{*} \cdot \hat{\mathrm{~A}} \psi+b^{*} \cdot \hat{\mathrm{~A}} \phi
kolbe2018hubbard_FO0032\langle H \psi, \phi\rangle=\left\langle\psi, H^{*} \phi\right\rangle
kolbe2018hubbard_FO0033H=H^{*}
kolbe2018hubbard_FO0034\hat{\mathrm{A}}=\hat{\mathrm{A}}^{\dagger}
kolbe2018hubbard_FO0035U^{\dagger}=U^{-1} \quad \Longleftrightarrow \quad U^{\dagger} U=U U^{\dagger}=1
kolbe2018hubbard_FO0036\vec{p} \rightarrow \frac{i}{\hbar} \nabla
kolbe2018hubbard_FO0037\vec{r} \rightarrow \hat{r}
kolbe2018hubbard_FO0038(2.5)
kolbe2018hubbard_FO0039x, y, z
kolbe2018hubbard_FO0040p_{x}, p_{y}, p_{z}
kolbe2018hubbard_FO0041\epsilon_{i j k}
kolbe2018hubbard_FO0042(2.7)
kolbe2018hubbard_FO0043\hat{J}^{2}=\hat{J}_{x}^{2}+\hat{J}_{y}^{2}+\hat{J}_{z}^{2}
kolbe2018hubbard_FO0044(2.8)
kolbe2018hubbard_FO0045\vec{J}
kolbe2018hubbard_FO0046\hat{J}^{2}
kolbe2018hubbard_FO0047J^{2}
kolbe2018hubbard_FO0048\hat{J}_{z}
kolbe2018hubbard_FO0049j
kolbe2018hubbard_FO0050m=-j,-j+1, \ldots, j
kolbe2018hubbard_FO0051(2 j+1)
kolbe2018hubbard_FO0052(2.9)
kolbe2018hubbard_FO0053\hat{J}_{x}
kolbe2018hubbard_FO0054\hat{J}^{+}
kolbe2018hubbard_FO0055\hat{J}^{-}
kolbe2018hubbard_FO0056\mathcal{H}_{s=1 / 2}
kolbe2018hubbard_FO0057|\uparrow\rangle
kolbe2018hubbard_FO0058\left\{|\uparrow\rangle=\binom{1}{0},|\downarrow\rangle=\binom{0}{1}\right\}
kolbe2018hubbard_FO0059z
kolbe2018hubbard_FO0060\alpha, \beta
kolbe2018hubbard_FO0061|\alpha|^{2}+|\beta|^{2}=1
kolbe2018hubbard_FO0062(2.15)
kolbe2018hubbard_FO00632 \times 2
kolbe2018hubbard_FO0064\sigma_{i}
kolbe2018hubbard_FO0065(2.20)
kolbe2018hubbard_FO0066\{A, B\}=A B+B A
kolbe2018hubbard_FO0067[-1,1]
kolbe2018hubbard_FO0068\vec{S}_{i} \vec{S} j
kolbe2018hubbard_FO0069T
kolbe2018hubbard_FO0070i, j \in(1, \ldots, N)
kolbe2018hubbard_FO0071\left|\Psi_{E_{n}, l}\right\rangle
kolbe2018hubbard_FO0072E_{n}, \beta=\frac{1}{k_{B} T}
kolbe2018hubbard_FO0073g_{n}
kolbe2018hubbard_FO0074\left|\psi_{g}\right\rangle
kolbe2018hubbard_FO0075T \rightarrow 0
kolbe2018hubbard_FO0076g_{0}
kolbe2018hubbard_FO0077\mathcal{H}_{i} i \in(1, \ldots, N)
kolbe2018hubbard_FO0078\mathcal{H}_{i}
kolbe2018hubbard_FO0079|\psi\rangle_{i} \in \mathcal{H}_{i}
kolbe2018hubbard_FO0080\hat{\mathrm{A}}_{i}
kolbe2018hubbard_FO0081i
kolbe2018hubbard_FO0082\mathcal{H}_{i} \in \mathcal{H}
kolbe2018hubbard_FO0083i \in(1, \ldots, N)
kolbe2018hubbard_FO0084N-1
kolbe2018hubbard_FO0085\mathcal{H}_{1}
kolbe2018hubbard_FO0086\mathcal{H}^{(+)}
kolbe2018hubbard_FO0087\mathcal{H}^{(-)}
kolbe2018hubbard_FO0088\mathcal{H}_{1}=\mathcal{H}^{(+)}
kolbe2018hubbard_FO0089\mathcal{H}_{1}=\mathcal{H}^{(-)}[7]
kolbe2018hubbard_FO0090\mathcal{V}
kolbe2018hubbard_FO0091\nu
kolbe2018hubbard_FO0092\pi \in S_{n}
kolbe2018hubbard_FO0093\operatorname{sign}(\pi)=1 \mathrm{bzw}
kolbe2018hubbard_FO0094\operatorname{sign}(\pi)=-1[9]
kolbe2018hubbard_FO0095i \in(1,2, \ldots, N)
kolbe2018hubbard_FO0096i \rightarrow \pi(i)
kolbe2018hubbard_FO0097\psi_{\alpha_{1} \alpha_{2} \ldots \alpha_{N}}\left(x_{1}, x_{2}, \ldots, x_{N}\right)
kolbe2018hubbard_FO0098\psi_{\alpha_{i}}\left(x_{j}\right)=\left\langle x_{j} \mid \alpha_{i}\right\rangle
kolbe2018hubbard_FO0099i, j \in(1,2, \ldots, N)
kolbe2018hubbard_FO0100x_{j}
kolbe2018hubbard_FO0101\alpha_{i}
kolbe2018hubbard_FO0102\left(\alpha_{i}=\alpha_{j}\right)
kolbe2018hubbard_FO0103n_{i \sigma}
kolbe2018hubbard_FO0104\sigma
kolbe2018hubbard_FO0105\left|n_{1 \sigma}, n_{2 \sigma} \ldots\right\rangle
kolbe2018hubbard_FO0106\hat{n_{i \sigma}}
kolbe2018hubbard_FO0107|\Psi\rangle
kolbe2018hubbard_FO01082 N
kolbe2018hubbard_FO0109(2.45)
kolbe2018hubbard_FO0110c_{i \sigma}^{\dagger}: F^{2 N} \rightarrow F^{2 N+1}
kolbe2018hubbard_FO0111|0\rangle=|0,0, \ldots\rangle \in F^{0}
kolbe2018hubbard_FO0112c_{i \sigma}: F^{2 N} \rightarrow F^{2 N-1}
kolbe2018hubbard_FO0113(2.51)
kolbe2018hubbard_FO0114N=3
kolbe2018hubbard_FO0115J_{i j}=J<0
kolbe2018hubbard_FO0116i, j \in(1,2,3)
kolbe2018hubbard_FO0117J_{13}
kolbe2018hubbard_FO0118J_{23}
kolbe2018hubbard_FO0119\vec{S}_{i}
kolbe2018hubbard_FO0120\vec{J}=\vec{L}+\vec{S}
kolbe2018hubbard_FO0121f
kolbe2018hubbard_FO0122\vec{R}_{i}
kolbe2018hubbard_FO0123\left|\vec{R}_{i}-\vec{R}_{j}\right|
kolbe2018hubbard_FO0124J_{i, j}=J\left(\left|\vec{R}_{i}-\vec{R}_{j}\right|\right)
kolbe2018hubbard_FO0125J_{i j}=J_{j i}
kolbe2018hubbard_FO0126x, y
kolbe2018hubbard_FO0127R=n_{1} a_{1}+n_{2} a_{2}+n_{3} a_{3}
kolbe2018hubbard_FO0128J>0
kolbe2018hubbard_FO0129J<0
kolbe2018hubbard_FO0130C u Z n
kolbe2018hubbard_FO0131C o, N i
kolbe2018hubbard_FO0132F e
kolbe2018hubbard_FO0133\mathbf{H}_{U}
kolbe2018hubbard_FO0134U
kolbe2018hubbard_FO0135\mathrm{H}_{t}
kolbe2018hubbard_FO0136t
kolbe2018hubbard_FO0137\mathbf{H}_{\epsilon}
kolbe2018hubbard_FO0138\epsilon_{i}=\frac{-U}{2}
kolbe2018hubbard_FO0139|\downarrow\rangle
kolbe2018hubbard_FO01402^{N}
kolbe2018hubbard_FO01410=|\downarrow\rangle
kolbe2018hubbard_FO01421=|\uparrow\rangle
kolbe2018hubbard_FO0143=2
kolbe2018hubbard_FO01442^{N} x N
kolbe2018hubbard_FO01452^{N}-1
kolbe2018hubbard_FO01462^{N} \times 2^{N}
kolbe2018hubbard_FO0147K
kolbe2018hubbard_FO0148H_{l m}=\langle l| H|m\rangle
kolbe2018hubbard_FO0149l, m \in\left(1, \ldots, 2^{N}\right)
kolbe2018hubbard_FO0150l
kolbe2018hubbard_FO0151m
kolbe2018hubbard_FO0152l, m
kolbe2018hubbard_FO0153i, j
kolbe2018hubbard_FO0154N \times N
kolbe2018hubbard_FO0155J_{i j}
kolbe2018hubbard_FO0156J_{i j}=0
kolbe2018hubbard_FO0157\hat{S}^{z}
kolbe2018hubbard_FO0158l=m
kolbe2018hubbard_FO0159k \in\left(1, \ldots, 2^{N}\right)
kolbe2018hubbard_FO0160\alpha_{k} \in \mathbb{R}
kolbe2018hubbard_FO0161|k\rangle
kolbe2018hubbard_FO01624^{N}
kolbe2018hubbard_FO0163[0,1,2,3]
kolbe2018hubbard_FO01640=|0\rangle, 1=|\downarrow\rangle, 2=|\uparrow\rangle
kolbe2018hubbard_FO01653=|\uparrow \downarrow\rangle
kolbe2018hubbard_FO0166\hat{n}_{\sigma}
kolbe2018hubbard_FO0167t, U, \epsilon, N
kolbe2018hubbard_FO0168N \times N-
kolbe2018hubbard_FO0169N=2
kolbe2018hubbard_FO01704^{N} \cdot 4^{N}
kolbe2018hubbard_FO0171\mathbf{H}_{t}
kolbe2018hubbard_FO0172k \in\left(1, \ldots, 4^{N}\right)
kolbe2018hubbard_FO0173i=1
kolbe2018hubbard_FO0174j=(1, \ldots, N)
kolbe2018hubbard_FO0175(1, \ldots, N)
kolbe2018hubbard_FO0176\hbar=1
kolbe2018hubbard_FO0177\frac{3}{4}
kolbe2018hubbard_FO0178\frac{1}{4}
kolbe2018hubbard_FO0179J^{\prime}
kolbe2018hubbard_FO0180J=1
kolbe2018hubbard_FO0181\alpha=\frac{J^{\prime}}{J}
kolbe2018hubbard_FO0182J^{\prime}<J
kolbe2018hubbard_FO0183j=-0.1
kolbe2018hubbard_FO0184j=-0.3
kolbe2018hubbard_FO0185j=-0.5
kolbe2018hubbard_FO0186j>2
kolbe2018hubbard_FO0187J^{\prime}=-0.1
kolbe2018hubbard_FO0188J^{\prime}=-0.3
kolbe2018hubbard_FO0189J^{\prime}=-0.5
kolbe2018hubbard_FO0190\alpha=1 / 2
kolbe2018hubbard_FO0191J^{\prime}>J
kolbe2018hubbard_FO0192J^{\prime} \geq J
kolbe2018hubbard_FO0193j=3,4,7,8
kolbe2018hubbard_FO0194J^{\prime}=-1
kolbe2018hubbard_FO0195j=5,10
kolbe2018hubbard_FO0196\left(J, J^{\prime}\right)<0
kolbe2018hubbard_FO0197J=-1
kolbe2018hubbard_FO0198J^{\prime} \rightarrow 0
kolbe2018hubbard_FO0199j=9
kolbe2018hubbard_FO0200(2, \ldots, 9)
kolbe2018hubbard_FO0201J^{\prime}=-0.26
kolbe2018hubbard_FO0202\simeq 0.5
kolbe2018hubbard_FO0203-\frac{3}{4}
kolbe2018hubbard_FO0204J^{\prime} \rightarrow-\infty
kolbe2018hubbard_FO0205J^{\prime}=-2,-5,-8
kolbe2018hubbard_FO0206J^{\prime} \rightarrow \infty
kolbe2018hubbard_FO0207\operatorname{Spin}(j=N-1)
kolbe2018hubbard_FO0208-J^{\prime}
kolbe2018hubbard_FO0209N=6,8,10
kolbe2018hubbard_FO0210-J^{\prime} \rightarrow 0
kolbe2018hubbard_FO0211-J^{\prime} \rightarrow \infty
kolbe2018hubbard_FO0212J^{\prime}=0
kolbe2018hubbard_FO0213t=1
kolbe2018hubbard_FO0214\beta=\frac{t}{u}
kolbe2018hubbard_FO0215\beta
kolbe2018hubbard_FO0216\beta \leq 1
kolbe2018hubbard_FO0217t^{\prime}
kolbe2018hubbard_FO0218\gamma=\frac{t^{\prime}}{t}
kolbe2018hubbard_FO0219\beta=\frac{t}{U}
kolbe2018hubbard_FO0220(t=1)
kolbe2018hubbard_FO0221\gamma=0.5
kolbe2018hubbard_FO0222j \geq 3
kolbe2018hubbard_FO0223\gamma \geq 1
kolbe2018hubbard_FO0224t^{\prime}=10
kolbe2018hubbard_FO0225t^{\prime}=1
kolbe2018hubbard_FO0226t=10
kolbe2018hubbard_FO0227\gamma<1
kolbe2018hubbard_FO0228\beta \geq 1
kolbe2018hubbard_FO0229U=1, t=1
kolbe2018hubbard_FO0230\gamma=t^{\prime} \ll 1
kolbe2018hubbard_FO0231t^{\prime}=0.4
kolbe2018hubbard_FO0232t^{\prime}=0.8
kolbe2018hubbard_FO0233t^{\prime}=0.1
kolbe2018hubbard_FO0234\beta=1
kolbe2018hubbard_FO0235\rightarrow \infty
kolbe2018hubbard_FO0236t^{\prime}=1.5
kolbe2018hubbard_FO0237t^{\prime}=100
kolbe2018hubbard_FO0238\alpha

Display Equations (61)

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kolbe2018hubbard_EQ0001_p007(2.2)\begin{aligned} c(|\phi\rangle+|\psi\rangle) & =c|\phi\rangle+c|\psi\rangle \\ (c+d)|\phi\rangle & =c|\phi\rangle+d|\phi\rangle \\ c(d|\phi\rangle) & =c d|\phi\rangle \end{aligned}crop
kolbe2018hubbard_EQ0002_p008(2.4)\vec{J}=\vec{r} \times \vec{p}crop
kolbe2018hubbard_EQ0003_p008(\2.5\)\hat{J}=\frac{\mathrm{i}}{\hbar} \hat{r} \times \nablacrop
kolbe2018hubbard_EQ0004_p008(\2.5\)\hat{J}_{x}=\frac{\mathrm{i}}{\hbar}\left(y \frac{\partial}{\partial z}-z \frac{\partial}{\partial y}\right) \quad ; \quad \hat{J}_{y}=\frac{\mathrm{i}}{\hbar}\left(z \frac{\partial}{\partial x}-x \frac{\partial}{\partial z}\right) \quad ; \quad \hat{J}_{z}=\frac{\mathrm{i}}{\hbar}\left(x \frac{\partial}{\partial y}-y \frac{\partial}{\partial x}\right)crop
kolbe2018hubbard_EQ0005_p008\left[\hat{J}_{x}, \hat{J}_{y}\right]=\mathrm{i} \hbar \hat{J}_{z} \quad ; \quad\left[\hat{J}_{y}, \hat{J}_{z}\right]=\mathrm{i} \hbar \hat{J}_{x} \quad ; \quad\left[\hat{J}_{z}, \hat{J}_{x}\right]=\mathrm{i} \hbar \hat{J}_{y}crop
kolbe2018hubbard_EQ0006_p009(2.6)\epsilon_{i j k}=\left\{\begin{aligned} +1, & \text { wenn ijk eine gerade Permutation von } 123 \text { ist } \\ -1, & \text { wen ijk eine ungerade Permutation von } 123 \text { ist } \\ 0, & \text { wenn mindestens zwei Indizes gleich sind } \end{aligned}\right.crop
kolbe2018hubbard_EQ0007_p009(\2.7\)\left[\hat{J}_{i}, \hat{J}_{j}\right]=\mathrm{i} \hbar \sum_{k} \hat{J}_{k} \epsilon_{i j k}crop
kolbe2018hubbard_EQ0008_p009(\2.8\)\left[\hat{J}_{i}, \hat{J}^{2}\right]=0 \quad i=x, y, zcrop
kolbe2018hubbard_EQ0009_p009(2.10)\begin{aligned} \hat{\mathbf{J}}^{2}|j, m\rangle & =\hbar^{2} j(j+1)|j, m\rangle \\ \hat{J}_{z}|j, m\rangle & =\hbar m|j, m\rangle \end{aligned}crop
kolbe2018hubbard_EQ0010_p009(2.11)\begin{aligned} \hat{J}^{+} & =\left(\hat{J}_{x}+\mathrm{i} \hat{J}_{y}\right) \\ \hat{J}^{-} & =\left(\hat{J}_{x}-\mathrm{i} \hat{J}_{y}\right) \end{aligned}crop
kolbe2018hubbard_EQ0011_p009(2.13)\left[\hat{J}_{z}, \hat{J}^{+}\right]=\hbar \hat{J}^{+} \quad, \quad\left[\hat{J}_{z}, \hat{J}^{-}\right]=-\hbar \hat{J}^{-} \quad, \quad\left[\hat{J}^{+}, \hat{J}^{-}\right]=2 \hbar \hat{J}_{z}crop
kolbe2018hubbard_EQ0012_p010(2.14)|s\rangle=\alpha|\uparrow\rangle+\beta|\downarrow\rangle=\binom{\alpha}{\beta}crop
kolbe2018hubbard_EQ0013_p010(\2.15\)\hat{\sigma}_{x}=\left(\begin{array}{ll} 0 & 1 \\ 1 & 0 \end{array}\right) \quad ; \quad \hat{\sigma}_{y}=\left(\begin{array}{cc} 0 & -\mathrm{i} \\ \mathrm{i} & 0 \end{array}\right) \quad ; \quad \hat{\sigma}_{z}=\left(\begin{array}{cc} 1 & 0 \\ 0 & -1 \end{array}\right) \quad ; \quad \hat{\sigma}_{0}=\left(\begin{array}{ll} 1 & 0 \\ 0 & 1 \end{array}\right)crop
kolbe2018hubbard_EQ0014_p010(2.16)\begin{aligned} \vec{S} & =\frac{\hbar}{2} \vec{\sigma} \\ \hat{S}_{i} & =\frac{\hbar}{2} \hat{\sigma}_{i} \quad i=x, y, z \end{aligned}crop
kolbe2018hubbard_EQ0015_p010(2.19)\begin{aligned} \mathbf{1}_{2} & =\hat{\sigma}_{x}^{2}+\hat{\sigma}_{y}^{2}+\hat{\sigma}_{z}^{2} \\ 2 \mathrm{i} \hat{\sigma}_{z} & =\left[\hat{\sigma}_{x}, \hat{\sigma}_{y}\right] \quad \text { und zyklisch } \\ \left\{\hat{\sigma}_{x}, \hat{\sigma}_{y}\right\} & =\left\{\hat{\sigma}_{y}, \hat{\sigma}_{z}\right\}=\left\{\hat{\sigma}_{z}, \hat{\sigma}_{x}\right\}=0 \end{aligned}crop
kolbe2018hubbard_EQ0016_p011(2.21)\begin{aligned} & \hat{S}_{x}=\frac{1}{2}\left(\hat{S}^{+}+\hat{S}^{-}\right) \\ & \hat{S}_{y}=\frac{1}{2 \mathrm{i}}\left(\hat{S}^{+}-\hat{S}^{-}\right) \end{aligned}crop
kolbe2018hubbard_EQ0017_p011(2.23)\hat{S}^{+}=\hbar\left(\begin{array}{ll} 0 & 1 \\ 0 & 0 \end{array}\right) \quad ; \quad \hat{S}^{-}=\hbar\left(\begin{array}{ll} 0 & 0 \\ 1 & 0 \end{array}\right)crop
kolbe2018hubbard_EQ0018_p011(2.25)\begin{aligned} \hat{S}^{+}|\downarrow\rangle & =\hbar|\uparrow\rangle & \hat{S}^{+}|\uparrow\rangle & =0 \\ \hat{S}^{-}|\uparrow\rangle & =\hbar|\downarrow\rangle & \hat{S}^{-}|\downarrow\rangle & =0 \\ \hat{S}_{z}|\uparrow\rangle & =\frac{\hbar}{2}|\uparrow\rangle & \hat{S}_{z}|\downarrow\rangle & =-\frac{\hbar}{2}|\downarrow\rangle \end{aligned}crop
kolbe2018hubbard_EQ0019_p011(2.28)\begin{aligned} -1 & <\left\langle\hat{S}_{i} \hat{S}_{j}\right\rangle_{\psi_{g}}<0 & & \text { antikorreliert. } \\ 0 & <\left\langle\hat{S}_{i} \hat{S}_{j}\right\rangle_{\psi_{g}}<1 & & \text { korreliert. } \\ 0 & =\left\langle\hat{S}_{i} \hat{S}_{j}\right\rangle_{\psi_{g}} & & \text { unkorreliert. } \\ 1 & =\left\langle\hat{S}_{i} \hat{S}_{j}\right\rangle_{\psi_{g}} & & \text { maximal korreliert. } \end{aligned}crop
kolbe2018hubbard_EQ0020_p011(2.31)\left\langle\vec{S}_{i} \vec{S}_{j}\right\rangle_{T}=\frac{1}{Z} \sum_{n} e^{\beta E_{n}} \sum_{l=1}^{g_{n}}\left\langle\Psi_{E_{n}, l}\right| \vec{S}_{i} \vec{S}_{j}\left|\Psi_{E_{n}, l}\right\ranglecrop
kolbe2018hubbard_EQ0021_p011(2.32)\left\langle\hat{S}_{i} \hat{S}_{j}\right\rangle_{\psi_{g}}=\frac{1}{g_{0}} \sum_{l=0}^{g_{0}}\left\langle\psi^{0, l}\right| \hat{S}_{i} \hat{S}_{j}\left|\psi^{0, l}\right\ranglecrop
kolbe2018hubbard_EQ0022_p012(2.33)\mathcal{H}=\mathcal{H}_{1} \otimes \mathcal{H}_{2} \otimes \ldots \otimes \mathcal{H}_{N-1} \otimes \mathcal{H}_{N}crop
kolbe2018hubbard_EQ0023_p012(2.34)|\psi\rangle=|\psi\rangle_{1} \otimes|\psi\rangle_{2} \otimes \ldots \otimes|\psi\rangle_{N-1} \otimes|\psi\rangle_{N}crop
kolbe2018hubbard_EQ0024_p012(2.35)\hat{\mathrm{A}}_{i}: \mathcal{H}_{i} \rightarrow \mathcal{H}_{i}crop
kolbe2018hubbard_EQ0025_p012(2.36)\overline{\mathrm{A}}_{1}+\ldots+\overline{\mathrm{A}}_{N}=\hat{\mathrm{A}}_{1} \otimes \hat{\mathrm{I}} \otimes \ldots \otimes \hat{\mathrm{I}}+\hat{\mathrm{I}} \otimes \hat{\mathrm{~A}}_{2} \otimes \ldots \otimes \hat{\mathrm{I}}+\ldots+\hat{\mathrm{I}} \otimes \ldots \otimes \hat{\mathrm{~A}_{N}}crop
kolbe2018hubbard_EQ0026_p013(2.37)\mathcal{H}=\mathcal{H}_{1}^{(1)} \otimes \mathcal{H}_{1}^{(2)} \otimes \ldots \otimes \mathcal{H}_{1}^{(N)}crop
kolbe2018hubbard_EQ0027_p013(2.38)\mathcal{V}\left(x_{1}, x_{2}, \ldots, x_{N}\right)=\sum_{\left\{\alpha_{i}\right\}} a_{\alpha_{1} \alpha_{2} \ldots \alpha_{N}} \nu_{\alpha_{1}}\left(x_{1}\right) \nu_{\alpha_{2}}\left(x_{2}\right) \ldots \nu_{\alpha_{N}}\left(x_{N}\right), \quad a_{\alpha_{i}} \in \mathbb{C}crop
kolbe2018hubbard_EQ0028_p013(2.40)\begin{array}{lr} \Psi\left(x_{1}, x_{2}, \ldots, x_{N}\right)=\operatorname{sign}(\pi) \Psi\left(x_{\pi(1)}, x_{\pi(2)}, \ldots, x_{\pi(N)}\right) & \text { für Fermionen } \\ \Phi\left(x_{1}, x_{2}, \ldots, x_{N}\right)=\Phi\left(x_{\pi(1)}, x_{\pi(2)}, \ldots, x_{\pi(N)}\right) & \text { für Bosonen } \end{array}crop
kolbe2018hubbard_EQ0029_p013(2.41)\Psi\left(x_{1}, x_{2}, \ldots, x_{N}\right)=\sum_{\left\{\alpha_{i}\right\}} a_{\alpha_{1} \alpha_{2} \ldots \alpha_{N}} \psi_{\alpha_{1} \alpha_{2} \ldots \alpha_{N}}\left(x_{1}, x_{2}, \ldots, x_{N}\right), \quad a_{\alpha_{1} \alpha_{2} \ldots \alpha_{N}} \in \mathbb{C}crop
kolbe2018hubbard_EQ0030_p013(2.42)\psi_{\alpha_{1} \alpha_{2} \ldots \alpha_{N}}\left(x_{1}, x_{2}, \ldots, x_{N}\right)=\frac{1}{\sqrt{N!}} \operatorname{det}\left(\begin{array}{ccc} \psi_{\alpha_{1}}\left(x_{1}\right) & \ldots & \psi_{\alpha_{N}}\left(x_{1}\right) \\ \vdots & \ddots & \vdots \\ \psi_{\alpha_{1}}\left(x_{N}\right) & \ldots & \psi_{\alpha_{N}}\left(x_{N}\right) \end{array}\right)crop
kolbe2018hubbard_EQ0031_p014(2.43)\left\langle n_{1 \sigma}, n_{2 \sigma}, \ldots \mid n_{1 \sigma}^{\prime}, n_{2 \sigma}^{\prime}, \ldots\right\rangle=\prod_{i, \sigma} \delta_{n_{i \sigma}, n_{i \sigma}^{\prime}}crop
kolbe2018hubbard_EQ0032_p014(2.44)|\Psi\rangle=\sum_{n_{1 \sigma}, n_{2 \sigma}, \ldots} a_{n_{1 \sigma}, n_{2 \sigma}, \ldots}\left|n_{1 \sigma}, n_{2 \sigma}, \ldots\right\rangle, \quad \text { wobei } 2 N=\sum_{i, \sigma} n_{i, \sigma}crop
kolbe2018hubbard_EQ0033_p014(\2.45\)\left.F^{(2 N)}=\mathcal{H}^{(+)}=\{|\Psi\rangle \in \mathcal{H}|\hat{\pi}| \Psi\rangle=(-1)^{\pi}|\Psi\rangle, \forall \pi \in S_{n}\right\}crop
kolbe2018hubbard_EQ0034_p014(2.46)c_{i \sigma}^{\dagger}\left|n_{1 \sigma}, \ldots, n_{i \sigma}, \ldots\right\rangle=\left(1-n_{i \sigma}(-1)^{\sum_{\sigma, j<i} n_{j \sigma}}\left|n_{1 \sigma}, \ldots, n_{i \sigma}+1, \ldots\right\rangle\right.crop
kolbe2018hubbard_EQ0035_p014(2.47)\left|n_{1 \uparrow} n_{1 \downarrow} \ldots\right\rangle=\prod_{i, \sigma} \frac{1}{\sqrt{n_{i \sigma!}}}\left(c_{i, \sigma}^{\dagger}\right)^{n_{i \sigma}}|0\ranglecrop
kolbe2018hubbard_EQ0036_p015(2.48)c_{i \sigma}\left|n_{1 \sigma}, \ldots, n_{i \sigma}, \ldots\right\rangle=n_{i \sigma}(-1)^{\sum_{\sigma, j<i} 2 n_{j \sigma}}\left|n_{1 \sigma}, \ldots, n_{i \sigma}-1, \ldots\right\ranglecrop
kolbe2018hubbard_EQ0037_p015(2.50)\begin{aligned} {\left[c_{i \sigma}, c_{j \sigma^{\prime}}^{\dagger}\right] } & =\delta_{i j} \delta_{\sigma \sigma^{\prime}} \\ {\left[c_{i \sigma}, c_{j \sigma^{\prime}}\right] } & =0 \\ {\left[c_{i \sigma}^{\dagger}, c_{j \sigma^{\prime}}^{\dagger}\right] } & =0 \end{aligned}crop
kolbe2018hubbard_EQ0038_p015(2.52)\hat{n}_{i \sigma}=c_{i \sigma}^{\dagger} c_{i \sigma}crop
kolbe2018hubbard_EQ0039_p015(2.53)\hat{n}_{i \sigma}\left|n_{1 \sigma}, \ldots, n_{i \sigma}, \ldots\right\rangle=n_{i \sigma}\left|n_{1 \sigma}, \ldots, n_{i \sigma}, \ldots\right\ranglecrop
kolbe2018hubbard_EQ0040_p017(3.1)\mathbf{H}_{\mathrm{Heis}}=-J \sum_{\langle i, j\rangle} \vec{S}_{i} \cdot \vec{S}_{j}crop
kolbe2018hubbard_EQ0041_p017(3.2)\vec{S}_{i} \cdot \vec{S}_{j}=S_{i}^{x} S_{j}^{x}+S_{i}^{y} S_{j}^{y}+S_{i}^{z} S_{j}^{z}crop
kolbe2018hubbard_EQ0042_p017(3.3)\mathbf{H}_{\mathrm{Heis}}=-J \sum_{\langle i, j\rangle} \frac{\hat{S}_{i}^{+} \hat{S}_{j}^{-}}{2}+\frac{\hat{S}_{i}^{-} \hat{S}_{j}^{+}}{2}+\hat{S}_{i}^{z} \hat{S}_{j}^{z}crop
kolbe2018hubbard_EQ0043_p019(3.4)\mathbf{H}_{\mathrm{Hub}}=\mathbf{H}_{U}+\mathbf{H}_{\epsilon}+\mathbf{H}_{t}crop
kolbe2018hubbard_EQ0044_p019(3.5)\mathbf{H}_{\mathrm{Hub}}=U \sum_{i=1}^{N} \hat{c}_{i, \uparrow}^{\dagger} \hat{c}_{i, \uparrow} \hat{c}_{i, \downarrow}^{\dagger} \hat{c}_{i, \downarrow}+\sum_{\sigma}\left(\sum_{i=1}^{N} \epsilon_{i} \hat{c}_{i, \sigma}^{\dagger} \hat{c}_{i, \sigma}-t \sum_{\langle i, j\rangle}\left(\hat{c}_{i, \sigma}^{\dagger} \hat{c}_{j, \sigma}+\hat{c}_{j, \sigma}^{\dagger} \hat{c}_{i, \sigma}\right)\right)crop
kolbe2018hubbard_EQ0045_p021(4.1)\hat{S}_{i}^{+} \hat{S}_{j}^{-}|Z u s t a n d\rangle \equiv \operatorname{SpinPlus}(i, \operatorname{SpinMinus}(j, Z u s t a n d))crop
kolbe2018hubbard_EQ0046_p021\left(\begin{array}{lll} 0 & \mathrm{~J} & 0 \\ 0 & 0 & \mathrm{~J} \\ \mathrm{~J} & 0 & 0 \end{array}\right)crop
kolbe2018hubbard_EQ0047_p021(4.2)\left\langle\hat{S}_{1} \hat{S}_{j}\right\rangle_{\psi_{g}}=\frac{1}{g_{0}} \sum_{l=0}^{g_{0}}\left\langle\psi^{0, l}\right| \frac{\hat{S}_{1}^{+} \hat{S}_{j}^{-}}{2}+\frac{\hat{S}_{1}^{-} \hat{S}_{j}^{+}}{2}+\hat{S}_{1}^{z} \hat{S}_{j}^{z}\left|\psi^{0, l}\right\ranglecrop
kolbe2018hubbard_EQ0048_p022(4.3)\left|\psi_{g}\right\rangle=\sum_{k=1}^{2^{N}} \alpha_{k}|k\rangle \quad \text { Heisenberg-Modell }crop
kolbe2018hubbard_EQ0049_p023(4.4)\hat{n}_{\uparrow}|Z u s t a n d\rangle=\hat{c}_{i \uparrow}^{\dagger} \hat{c}_{j \uparrow}|Z u s t a n d\rangle \Leftrightarrow \operatorname{CupDagger}(i, \operatorname{Cup}(j, \text { Zustand }))crop
kolbe2018hubbard_EQ0050_p023\left(\begin{array}{lll} 0 & \mathrm{t} & 0 \\ 0 & 0 & \mathrm{t} \\ 0 & 0 & 0 \end{array}\right)crop
kolbe2018hubbard_EQ0051_p023(4.5)\hat{c}_{j, \uparrow}^{\dagger} \hat{c}_{j, \downarrow}^{\dagger}|0\rangle_{j}=|\uparrow \downarrow\rangle_{j} \quad \quad \hat{c}_{j, \downarrow}^{\dagger} \hat{c}_{j, \uparrow}^{\dagger}|0\rangle_{j}=-\hat{c}_{j, \uparrow}^{\dagger} \hat{c}_{j, \downarrow}^{\dagger}|0\rangle_{j}=-|\uparrow \downarrow\rangle_{j}crop
kolbe2018hubbard_EQ0052_p023(4.6)|0,0\rangle=[0,0] \quad|\downarrow, \downarrow\rangle=[1,1] \quad|\uparrow, \uparrow\rangle=[2,2] \quad|\uparrow \downarrow, \uparrow \downarrow\rangle=[3,3]crop
kolbe2018hubbard_EQ0053_p023(4.7)\begin{array}{rll} |0, \downarrow\rangle=[0,1] & \rightarrow & |\downarrow, 0\rangle=[1,0] \\ |\downarrow, 0\rangle=[1,0] & \rightarrow & |0, \downarrow\rangle=[0,1] \\ |0, \uparrow\rangle=[0,2] & \rightarrow & |\uparrow, 0\rangle=[2,0] \\ |\uparrow, 0\rangle=[2,0] & \rightarrow & |0, \uparrow\rangle=[0,2] \end{array}crop
kolbe2018hubbard_EQ0054_p024(4.8)\begin{array}{lll} |\uparrow, \uparrow \downarrow\rangle=[1,3] & \rightarrow & |\uparrow \downarrow, \uparrow\rangle=[3,1] \\ |\downarrow, \downarrow \uparrow\rangle=[1,3] & \rightarrow & |\uparrow \downarrow, \downarrow\rangle=[3,2] \\ |\uparrow \downarrow, \uparrow\rangle=[3,1] & \rightarrow & |\uparrow, \uparrow \downarrow\rangle=[1,3] \\ |\uparrow \downarrow, \downarrow\rangle=[3,2] & \rightarrow & |\downarrow, \uparrow \downarrow\rangle=[2,3] \end{array}crop
kolbe2018hubbard_EQ0055_p024(4.9)\begin{aligned} |\uparrow, \downarrow\rangle=[1,2] & \rightarrow & |\uparrow \downarrow, 0\rangle+|0, \uparrow \downarrow\rangle=[3,0]+[0,3] \\ |\downarrow, \uparrow\rangle=[2,1] & \rightarrow & -|\uparrow \downarrow, 0\rangle-|0, \uparrow \downarrow\rangle=-[3,0]-[0,3] \\ |\uparrow \downarrow, 0\rangle=[3,0] & \rightarrow & |\uparrow, \downarrow\rangle-|\downarrow, \uparrow\rangle=[2,1]-[1,2] \\ |0, \uparrow \downarrow\rangle=[0,3] & \rightarrow & |\uparrow, \downarrow\rangle-|\downarrow, \uparrow\rangle=[1,2]-[2,1] \end{aligned}crop
kolbe2018hubbard_EQ0056_p024(4.10)\mathbf{H}_{\epsilon}+\mathbf{H}_{U}=\sum_{i=1}^{N}\left(\epsilon_{i} \cdot\left(\hat{n}_{i, \uparrow}+\hat{n}_{i, \downarrow}\right)+U_{i} \cdot \hat{n}_{i, \uparrow} \hat{n}_{i, \downarrow}\right)crop
kolbe2018hubbard_EQ0057_p024(4.11)\langle l| \mathbf{H}_{\epsilon}+\mathbf{H}_{U}|m\rangle= \begin{cases}\epsilon_{l m}+U_{l m} & \text { wenn } l=m \text { ist. } \\ 0 & \text { wenn } l \neq m \text { ist. }\end{cases}crop
kolbe2018hubbard_EQ0058_p025(4.12)\hat{S}_{i}^{+}=\hat{c}_{i, \uparrow}^{\dagger} \hat{c}_{i, \downarrow} \quad ; \quad \hat{S}_{i}^{-}=\hat{c}_{i, \downarrow}^{\dagger} \hat{c}_{i, \uparrow} \quad ; \quad \hat{S}_{i}^{z}=\frac{1}{2}\left(\hat{c}_{j, \uparrow}^{\dagger} \hat{c}_{j, \uparrow}-\hat{c}_{j, \downarrow}^{\dagger} \hat{c}_{j, \downarrow}\right)crop
kolbe2018hubbard_EQ0059_p025(4.12)\begin{aligned} C_{1 j}= & \frac{1}{g_{0}} \sum_{l=0}^{g_{0}}\left\langle\psi^{0, l}\right| \frac{1}{2}\left(\hat{c}_{1, \uparrow}^{\dagger} \hat{c}_{1, \downarrow} \hat{c}_{j, \downarrow}^{\dagger} \hat{c}_{j, \uparrow}+\hat{c}_{1, \downarrow}^{\dagger} \hat{c}_{1, \uparrow} \hat{c}_{j, \uparrow}^{\dagger} \hat{c}_{j, \downarrow}\right) \\ & +\frac{1}{4}\left(\hat{c}_{1, \uparrow}^{\dagger} \hat{c}_{1, \uparrow}-\hat{c}_{1, \downarrow}^{\dagger} \hat{c}_{1, \downarrow}\right)\left(\hat{c}_{j, \uparrow}^{\dagger} \hat{c}_{j, \uparrow}-\hat{c}_{j, \downarrow}^{\dagger} \hat{c}_{j, \downarrow}\right)\left|\psi^{0, l}\right\rangle \\ = & \frac{1}{g_{0}} \sum_{l=0}^{g_{0}}\left\langle\psi^{0, l}\right| \frac{1}{2}\left(\hat{c}_{1, \uparrow}^{\dagger} \hat{c}_{1, \downarrow} \hat{c}_{j, \downarrow}^{\dagger} \hat{c}_{j, \uparrow}+\hat{c}_{1, \downarrow}^{\dagger} \hat{c}_{1, \uparrow} \hat{c}_{j, \uparrow}^{\dagger} \hat{c}_{j, \downarrow}\right) \\ & +\frac{1}{4}\left(\hat{c}_{1, \uparrow}^{\dagger} \hat{c}_{1, \uparrow} \cdot \hat{c}_{j, \uparrow}^{\dagger} \hat{c}_{j, \uparrow}-\hat{c}_{1, \uparrow}^{\dagger} \hat{c}_{1, \uparrow} \cdot \hat{c}_{j, \downarrow}^{\dagger} \hat{c}_{j, \downarrow}-\hat{c}_{1, \downarrow}^{\dagger} \hat{c}_{1, \downarrow} \cdot \hat{c}_{j, \uparrow}^{\dagger} \hat{c}_{j, \uparrow}+\hat{c}_{1, \downarrow}^{\dagger} \hat{c}_{1, \downarrow} \cdot \hat{c}_{j, \downarrow}^{\dagger} \hat{c}_{j, \downarrow}\right)\left|\psi^{0, l}\right\rangle \end{aligned}crop
kolbe2018hubbard_EQ0060_p025(4.13)\begin{aligned} \left\langle\hat{S}_{i} \hat{S}_{j}\right\rangle_{\psi_{g}}= & \frac{1}{g_{0}} \sum_{l=0}^{g_{0}}\left\langle\psi^{0, l}\right| \frac{1}{2}\left(\hat{c}_{1, \uparrow}^{\dagger} \hat{c}_{1, \downarrow} \hat{c}_{j, \downarrow}^{\dagger} \hat{c}_{j, \uparrow}+\hat{c}_{1, \downarrow}^{\dagger} \hat{c}_{1, \uparrow} \hat{c}_{j, \uparrow}^{\dagger} \hat{c}_{j, \downarrow}\right) \\ & +\frac{1}{4}\left(\hat{n}_{1, \uparrow} \hat{n}_{j, \uparrow}-\hat{n}_{1, \uparrow} \hat{n}_{j, \downarrow}-\hat{n}_{1, \downarrow} \hat{n}_{j, \uparrow}+\hat{n}_{1, \downarrow} \hat{n}_{j, \downarrow}\right)\left|\psi^{0, l}\right\rangle \end{aligned}crop
kolbe2018hubbard_EQ0061_p025(4.14)\left|\psi_{g}\right\rangle=\sum_{k=1}^{4^{N}} \alpha_{k}|k\rangle \quad \text { Hubbard-Modell }crop

TikZ & Tables (22; 9 rendered to SVG)

#typecaptionLaTeX sourceSVG render
1Diagramcrop
2DiagramAbbildung 1.1: Darstellung einer Heisenberg-Kette mit Übernächster-Nachbar-Wechselwirkung und sieben Plätzencrop
3DiagramAbbildung 2.1: Ein Sketch zu dem Phänomen der Frustration.crop
4DiagramAbbildung 3.1: Eine lineare Heisenberg-Kette mit N Plätzen.crop
5DiagramAbbildung 3.2: Lineare Hubbard-Kette mit N Plätzen.crop
6Diagramcode listingfunction spin_state_generator(N) x=collect(1:N) states=[] for j in 0:2^N-1 stat=copy(digits!(x,j,2)) push!(states, stat) end return (states) end
function spin_state_generator(N)

    x=collect(1:N)

    states=[]

        for j in 0:2^N-1

                stat=copy(digits!(x,j,2))

            push!(states, stat)

        end

    return (states)

end
7Diagramcode listingfunction SpinPlus(i,state) zustand=copy(state) if(state==0) zustand=0 else if(zustand[i]==0) zustand=0 elseif(zustand[i]==1) zustand[i]=0 end
function SpinPlus(i,state)

            zustand=copy(state)

    if(state==0)

            zustand=0

    else

        if(zustand[i]==0)

            zustand=0

        elseif(zustand[i]==1)

            zustand[i]=0

        end
8Diagramcode listingend return zustand end
end

    return zustand

end
9Diagramcode listingfunction fermion_state_generator(N) x=collect(1:N) states=[] for j in 0:4^N-1 stat=copy(digits!(x, j,4)) push!(states, stat) end return states end
function fermion_state_generator(N)

    x=collect(1:N)

    states=[]

        for j in 0:4^N-1

            stat=copy(digits!(x, j,4))

            push!(states, stat)

        end

    return states

end
10Diagramcode listingfunction CupDagger(i, vec) #0=0 2=up 1=down 3= updown states=copy (vec) if states==0 return 0 else if(states[i]==0) states[i]=2 elseif(states[i]==1) states[i]=3 else return 0 end end return states
function CupDagger(i, vec)

    #0=0 2=up 1=down 3= updown

    states=copy (vec)

    if states==0

                return 0

    else

        if(states[i]==0)

            states[i]=2

            elseif(states[i]==1)

            states[i]=3

            else

            return 0

        end

    end

        return states
11Diagramcode listingend
end
12DiagramAbbildung 5.3: Eine Schematische Darstellung einer Heisenberg-Kette mit Über-nächster Nachbar Wechselwirkung.crop
13DiagramAbbildung 5.6: Ein Sketch einer Heisenberg-Kette mit Über-nächster Nachbar Wechselwirkung und sechs Plätzen.crop
14Table\begin{tabular}{rl} Erarbeitet von: & Alexander Kolbe \\ Hochschule: & Universität zu Köln \\ Betreuer: & apl. Prof. Dr. Ralf Bulla \\ Zweitgutachter: & PD. Dr. Rochus Klesse \\ &\\ \multicolumn{2}{c}{Sommer-Semester 2018} \end{tabular}
15DiagramDarstellung einer Heisenberg-Kette mit Übernächster-Nachbar-Wechselwirkung und sieben Plätzen\begin{tikzpicture} \SetGraphUnit{5} \node[circle, outer color=blue!60!black,inner color=white, minimum width=1cm] (1) at (-6,-2) {$1$}; \node[circle, outer color=blue!60!black,inner color=white, minimum width=1cm] (2) at ( -4 ,0) {$2$}; \node[circle, outer color=blue!60!black,inner color=white, minimum width=1cm] (3) at ( -2,-2) {$3$}; \node[circle, outer color=blue!60!black,inner color=white
16DiagramEin Sketch zu dem Phänomen der Frustration.\begin{tikzpicture} \SetGraphUnit{3} \node[circle, outer color=blue!60!black,inner color=white, minimum width=1cm] (1) at ( -2,-2) {$\uparrow$}; \node[circle, outer color=blue!60!black,inner color=white, minimum width=1cm] (2) at (0 ,0) {$\downarrow$}; \node[circle, outer color=blue!60!black,inner color=white, minimum width=1cm] (3) at (2,-2) {$?$}; \tikzset{EdgeStyle/.append style = {b
17DiagramEine lineare Heisenberg-Kette mit N Plätzen.\begin{tikzpicture} \SetGraphUnit{8} \node[color=black] (0) at (-7,0) {$n=$}; \node[circle, outer color=blue!60!black,inner color=white, minimum width=0.8cm] (1) at (-6,0) {$1$} node[color=violet] at (-5,0.4) {$J_{12}$}; \node[circle, outer color=blue!60!black,inner color=white, minimum width=0.8cm] (2) at (-4 ,0) {$2$} node[color=violet] at (-3,0.4) {$J_{23}$}; \node[circle, outer color=
18DiagramLineare Hubbard-Kette mit N Plätzen.\begin{tikzpicture} \SetGraphUnit{8} \node[color=black] (0) at (-7,0) {$n=$}; \node[circle, outer color=green!60!black,inner color=white, minimum width=0.8cm] (1) at (-6,0) {$1$} node[color=red] at (-6,-0.8) {$\epsilon_1,U_1$} node[color=blue] at (-5,0.4) {$t_{12}$}; \node[circle, outer color=green!60!black,inner color=white, minimum width=0.8cm] (2) at (-4 ,0) {$2$} node[color=red] at (-4
19Table\begin{tabular}{ccc} 0 & J & 0 \\ 0 & 0 & J \\ J & 0 & 0 \end{tabular}
20Table\begin{tabular}{ccc} 0 & t & 0 \\ 0 & 0 & t \\ 0 & 0 & 0 \end{tabular}
21DiagramEine Schematische Darstellung einer Heisenberg-Kette mit Über-nächster Nachbar Wechselwirkung.\begin{tikzpicture} \SetGraphUnit{3} \Vertex{3} \WE(3){2} \WE(2){1} \EA(3){4} \EA(4){5} \EA(5){6} \tikzset{EdgeStyle/.append style = {bend left = 0}} \Edge[label = $J$](1)(2) \Edge[label = $J$](2)(3) \Edge[label = $J$](3)(4) \Edge[label = $J$](4)(5) \Edge[label = $J$](5)(6) \tikzset{EdgeStyle/.append style = {bend left = 50}} \Edge[label = $J'$](3)(1) \Edge[label =
22DiagramEin Sketch einer Heisenberg-Kette mit Über-nächster Nachbar Wechselwirkung und sechs Plätzen.\begin{tikzpicture} \SetGraphUnit{5} \node[color=black] (0) at (-7,0) {$n=$}; \node[circle, outer color=blue!60!black,inner color=white, minimum width=0.8cm] (1) at (-6,0) {$1$} node[color=violet] at (-5,0.4) {$J'$}; \node[circle, outer color=blue!60!black,inner color=white, minimum width=0.8cm] (2) at (-4 ,0) {$2$} node[color=violet] at (-3,0.4) {$J$}; \node[circle, outer color=blue!60!b