It is known that defect-free crystals having a wide gap in the phonon spectrum can support gap discrete breathers (DB) being spatially localized large amplitude vibrational modes with frequencies within theband gap. One of examples of such crystal type is the intermetallic alloy Pt3Al with a a gap in the phonon spectrum caused by large difference in the atomic masses of the components. In the present work, the first attempts of the molecular dynamics modelling studiesof the DB close to atomically smooth (100) orientation surface of the crystal is presented. It is shown that properties of the DB depend essentially on the composition of the surface atomic plane, which for the considered crystal can consist of Pt atoms or both of Pt and Al atoms in equal proportions. The results obtained can significantly contribute to the development of surface physics science.