Diode RLC represention
Yes, diodes can be modeled as RLC circuits, depending on the precision of the description you wish to obtain. Also, it is to be kept in mind that such a modeling can be considered valid only in well defined circumnstances (e.g. In steady-state, the model is valid in the on state, but not in the off state --may be obvious, but I prefer to specify that--).

The simplest model you get (in steady-state) is the one that considers the diode to be an open circuit when in the off state and a short circuit when in the on state. A slightly more accurate model cosiders the diode as a simple generator (let's say, of 0.7 V) when in the on state. With such a model, this circuit







simulate this circuit &ndash; Schematic created using CircuitLab

is equivalent to this (when the switch is closed and the diode turns on):







simulate this circuit

If you are looking for an AC representation (or should I say a small signal representation), the dinamic behaviour of a diode comprises at least a resistance to model the slope of its characteristic curve and a parallel capacitor to model its attitude in accumulating charge when in on state, to be discharged in order to become reverse biased.