Limitations of the efficiency of the existing solar cells motivate continuous search for new technological solutions that might lead to more efficient photovoltaic conversion. Among systems that are investigated for possible use in solar energy conversion devices are semiconductor quantum dots. A few ways of employing these nanometer-scale objects in the photoconversion process have been proposed [1, 2], one of which is multiple exciton generation in nanocrystals. Such an effect, consisting in generation of two or more electron–hole pairs by a single absorbed photon, has been observed in a few recent experiments performed on nanocrystals formed of various narrow-gap semiconductors [3–5]. It is a matter of discussion whether the excitons are created coherently during the absorption process or incoherently, due to carrier kinetics involving some kind of dissipative processes at a later time. In any case, the process results from the Coulomb coupling between electron and trion states. As a result, an intraband transition (relaxation) of the electron may be accompanied by the creation of another electron–hole pair, as shown in Fig. 1a. This Auger-type process is referred to as impact ionization. Let us note that the hole, which is initially created in the same confined state as the electron, does not take part in the impact ionization process. In this paper we formulate and study a simple theoretical model of coherent multiple exciton generation by a single high-energy photon absorbed in an InAs nanocrystal. We calculate the interband Coulomb matrix element between an excited electron state and a ground state trion. We determine the degree of mixing