in this investigation the effect of external field on the electron density of nanostructures of cds, cdse, cdte, gaas and polymeric structure of three, four, five and six units of cds as a kind of nanosolar cells has been studied theoretically. as modeling this system in nanodimension, molecular structures has used. specific properties of molecular structures permit us to consider different symmetry and size for the system, such as linear and facial array. in linear array cd atoms and s atoms are in the straight line but in facial array cd atoms are parallel with s atoms. we should denote the best array of atoms. different array has been optimized by lanl2dz method. the best array has the minimum energy so it is more stable than the other. theoretical analysis of the topology of electron density distribution such as the effect of external field on the electron density of the best array was performed within the quantum theory of atoms in molecules (qtaims). it should be noted that properties were studied using the bonding critical points. in qtaim theory these critical points are very important in the survey of chemical bonding properties.