# PLaSK User Manual

#### Page Contents

- OldDiffusion2D

# OldDiffusion2D

<electrical solver="OldDiffusion2D">

  Corresponding Python class: `electrical.olddiffusion.OldDiffusion2D`.

  Two-dimensional diffusion solver in Cartesian geometry.

  Attributes:

    - name (`required`) – Solver name.

  Contents:
    <geometry>

      Geometry for use by this solver.

      Attributes:

        - ref (`required`) – Name of a Cartesian2D geometry defined in the `<geometry>` section.

    <mesh>

      Optional Regular mesh used by this solver.

      Attributes:

        - ref (`required`) – Name of a Regular mesh defined in the `<grids>` section.

    <config>

      Solver configuration.

      Attributes:

        - fem-method – Order of the finite-element method. (`linear` or `parabolic`, default is `parabolic`)

        - accuracy – Required relative accuracy. (float (%), default 0.01 %)

        - abs-accuracy – Required absolute minimal concentration accuracy. (float (cm-3), default 5000000000000000.0 cm-3)

        - maxiters – Maximum number of allowed iterations before attempting to refine mesh. (int, default 20)

        - maxrefines – Maximum number of allowed mesh refinements. (int, default 5)

        - interpolation – Current density interpolation method name. (`linear` or `spline`, default is `spline`)