A novel method to predict nanofilm morphology on arbitrary-topographical substrate

•A novel DCT based method is proposed to predict nanofilms morphology.•A general analytical criterion of nanofilm fully conformal onto substrate is derived.•The method can apply to substrates with arbitrary topography.•The method can work at both micro- and nano- scales.•The method is very efficient, taking only about 10−4 of time cost of MD simulations.