Anti-Bonding molecular orbitals are formed by the destructive overlapping of atomic orbitals takes place and the probability of finding electrons is very low in the case of anti-bonding molecular orbitals.
Antibonding orbitals are represented by
In these orbitals, the electron density in the internuclear distance is low due to which the nuclei are directly exposed to each other and thus experience high repulsive forces.
Due to high repulsive forces, the energy of antibonding orbitals is quite high.