# OCTCurrentFunctional

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#### OCTCurrentFunctional

Section Calculation Modes::Optimal Control
Type integer
Default oct_no_curr

(Experimental) The variable OCTCurrentFunctional describes which kind of current target functional $J1_c[j]$ is to be used.

Options:

• oct_no_curr:
No current functional is used, no current calculated.
• oct_curr_square:
Calculates the square of current $j$: $J1_c[j] = {\tt OCTCurrentWeight} \int{\left| j(r) \right|^2 dr}$. For OCTCurrentWeight < 0, the current will be minimized (useful in combination with target density in order to obtain stable final target density), while for OCTCurrentWeight > 0, it will be maximized (useful in combination with a target density in order to obtain a high-velocity impact, for instance). It is a static target, to be reached at total time.
• oct_max_curr_ring:
Maximizes the current of a quantum ring in one direction. The functional maximizes the $z$ projection of the outer product between the position $\vec{r}$ and the current $\vec{j}$: $J1[j] = {\tt OCTCurrentWeight} \int{(\vec{r} \times \vec{j}) \cdot \hat{z} dr}$. For OCTCurrentWeight > 0, the current flows in counter-clockwise direction, while for OCTCurrentWeight < 0, the current is clockwise.
• oct_curr_square_td:
The time-dependent version of oct_curr_square. In fact, calculates the square of current in time interval [OCTStartTimeCurrTg, total time = TDMaximumIter * TDTimeStep]. Set TDPropagator = crank_nicolson.

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