By default, the kick function will be a dipole. This will change if (1) the variable
TDDeltaUserDefined is present in the inp file, or (2) if the block TDKickFunction
is present in the inp file. If both are present in the inp file, the TDKickFunction
block will be ignored. The value of TDDeltaUserDefined should be a string describing
the function that is going to be used as delta perturbation.