FIGURE 4.

Transfer times (reciprocal of transfer rates) between the Lhca subunits and the PSI core. The subscript “+” of the Lhca subunits indicates that the neighboring linker chlorophylls belonging to the same chain are included with a given subunit. A Boltzmann equilibrium of donor states is assumed before transfer (see text). The first number corresponds to a spectrally refined hybrid Hamiltonian (model C in Table 1), whereas the second number (in parentheses) corresponds to a uniform site energy distribution for non-conserved chlorophylls (model F in Table 1). We conclude that inter-Lhca transfer rates cannot be assigned reliably due to the parameter sensitivity of these values on site energy assignments. The collective transfer time from all Lhca subunits to the PSI core (including gap chlorophylls) is 2.1 ps (becoming 1.5 ps in the uniform site energy model). The transfer time from the chlorophyll-b forms to the chlorophyll-a pool of Lhca subunits, computed similarly (according to model C in Table 1), is 288 fs.