Molecular dynamics simulations are performed on capped and uncapped PbSe nanocrystals, employing newly developed classical interaction potentials Here, we show that two uncapped nanocrystals fuse efficiently via direct surface attachment, even if they are initially misaligned In sharp contrast to the general belief, interparticle dipole interactions do not play a significant role in this "oriented attachment" process Furthermore, it is shown that presumably polar, capped PbSe {111} facets are never fully Pb- or Se-terminated@en