(Experimental)
If OCTTargetOperator = oct_tg_hhg, the target is the harmonic emission spectrum.
In that case, you must supply an OCTOptimizeHarmonicSpectrum block in the inp
file. The target is given, in general, by:
where $H(\omega)$ is the harmonic spectrum generated by the system, and
$\alpha(\omega)$ is some function that determines what exactly we want
to optimize. The role of the OCTOptimizeHarmonicSpectrum block is to determine
this $\alpha(\omega)$ function. Currently, this function is defined as:
where $\omega_0$ is the carrier frequency. $M$ is
the number of columns in the OCTOptimizeHarmonicSpectrum block. The values of L will be listed
in the first row of this block; $\alpha_L$ in the second row, and $a_L$ in
the third.