Figure 3
From: Singlet fission for quantum information and quantum computing: the parallel JDE model
Zero-field energy and selection rules. (a) Energy-level correlation diagram of the JDE model in zero applied field. Interaction energies and splittings decrease in magnitude going from left to right. The sign of J orders the states of total S; we choose \(J<0\) in analogy to Hund’s rule. The choice \(D>0\) corresponds to literature values for pentacene23. D is the second largest energy scale and it lifts the degeneracy of states with different magnitudes of the total spin projection quantum number \(|M|=0,1,2\). (b) The Q states are linear combinations of degenerate pairs of \(^5\text {TT}_{\pm M}\) states with Cartesian subscripts that indicate analogies to the d-orbitals. Transitions from \(^1\text {TT}\) are only allowed to two Q states (black). The \(Q_{z^2}\) state may be populated through a non-adiabatically fast interconversion process which goes as \(k_{\text {fast}}\sim D^{2}\). A much slower process \(k_\text {slow}\sim E^{2}\) allows transition from the \(^1\text {TT}\) state to the \(Q_{x^2-y^2}\) state.
