The method of tunneling: currents developed earlier by one of the authors i
s applied to study electron tunneling dynamics in a model organometallic do
nor-bridge-acceptor system, in which the donor is a blue copper center in t
he reduced form, the bridge is a polypeptide (5 glycine residues), and the
acceptor is the -HisRu(III)bpy(2)Im complex. This system mimics pretty clos
ely the major amino acid tunneling path in Ru-modified azurin studied by Gr
ay and co-workers recently. It is demonstrated that the tunneling matrix el
ement as small as 10(-4) cm(-1) can be reliably evaluated using ab initio t
unneling currents method. The method consists of an ab initio electronic st
ructure calculation of the spatial distribution of quantum mechanical flux
in the tunneling transition occurring in the system, when an electron/hole
tunnels from the donor site in the molecule to the acceptor site. The analy
sis is based on the calculation of two diabatic nonorthogonal electronic st
ates corresponding to localization of a tunneling electron on donor and acc
eptor sites, respectively, and subsequent evaluation of the matrix element
of current density operator between these two states. All electrons in the
system are taken into account at the Hartree-Fock level, and therefore the
method allows one to examine the reaction of the background electrons to th
e tunneling charge in a self-consistent way. Results for this system confir
m earlier reported finding that in the tunneling flow there exist quantized
vortices, similar to those of a superfluid liquid, such as liquid He.