Notation

$x$	...	Scalar
$\ensuremath{\mathitbf{x}}$	...	Vector
$\ensuremath{{\underline{A}}}$	...	Matrix
$A_{ij}$	...	Elements of the matrix ${\underline{A}}$
${\,\mathrm{tr}\left(\ensuremath{{\underline{A}}}\right)}$	...	Trace of the matrix ${\underline{A}}$
$\ensuremath{{\mathrm{\hat{X}}}}$	...	Tensor
$\ensuremath{\mathitbf{x}} \ensuremath{\cdot}\ensuremath{\mathitbf{y}}$	...	Scalar (in) product
$\ensuremath{\mathitbf{x}} \ensuremath{\times}\ensuremath{\mathitbf{y}}$	...	Vector (ex) product
$\ensuremath{\mathitbf{x}} \ensuremath{\otimes}\ensuremath{\mathitbf{y}}$	...	Tensor product
$\partial_t(\cdot)$	...	Partial derivative with respect to $t$
$\ensuremath{\ensuremath{\mathitbf{\nabla}}}$	...	Nabla operator
$\ensuremath{\ensuremath{\ensuremath{\mathitbf{\nabla}}}}x$	...	Gradient of $x$
$\ensuremath{\ensuremath{\ensuremath{\mathitbf{\nabla}}}\ensuremath{\cdot}}\ensuremath{\mathitbf{x}}$	...	Divergence of $\ensuremath{\mathitbf{x}}$
$\ensuremath{\langle \! \langle \cdot \rangle \! \rangle}$	...	Statistical average
$\ensuremath{\langle \cdot \rangle}$	...	Normalized statistical average
$\Gamma(\cdot)$	...	Gamma function
$f(\mathbf{r},\mathbf{k},t)$	...	Distribution function
$\ensuremath{\mathcal{Q}(\cdot)}$	...	Collision operator
$\ensuremath{{\cal{H}}}$	...	Hamiltonian operator
$\ensuremath{\mathrm{s}_\nu}$	...	Carrier charge sign
$\ensuremath{\{\cdot,\cdot\}}$	...	Poisson bracket

M. Wagner: Simulation of Thermoelectric Devices