Any analytical expression allowed by the Composer's Expression-field can be written in the textfield. The wavefunction can be used either directly, or it can be numerically normalized by checking the "Normalize output"-checkbox. In this case the node also displays the normalization-constant multiplied onto the expression. Numerical normalization of wavefunctions is described on the Normalization-page.
Except for input-errors, this node can show slightly weird errors saying something about "parse error matching struct...". This kind of error tells the user that the expression written in the textbox is not valid.