  The excitation energy transfer (EET) in Fenna-Matthews-Olson (FMO) complex
has been investigated in the presence of realistic inhomogeneous protein
environment around different bacteriochlorophyll-a (BChla) sites of a 8-site
monomer. We studied the effect of initial coherence and the 8th chromophore on
the EET dynamics considering relative orientation of transition dipole moments
of all the BChla sites. We choose femtosecond coherent laser pulse to prepare
initial coherent superposition state. Our non-Markovian simulation reveals that
the initial coherence between excited states of BChla sites accelerate the
excitation energy transfer process as compared to initial mixed state. Even
more impressively, in the presence of the 8th chromophore, the initial pure
state relaxes much faster than in the 7-site monomer. Hence the inclusion of
8th chromophore additionally enhances the EET relaxation.
