ction</i>: Time-Dependent::Response
<br/><i>Type</i>: float
<br/><br> When no laser is applied, a delta (in time) perturbation with
 strength <tt>TDDeltaStrength</tt> can be applied. This is used to
 calculate, <i>e.g.</i>, the linear optical spectra. If the ions are
 allowed to move, the kick will affect them also.
 The electric field is -(\hbar <i>k</i> / <i>e</i>) delta(<i>t</i>) for a dipole with
 zero wavevector, where <i>k</i> = <tt>TDDeltaStrength</tt>, which causes
 the wavefunctions instantaneously