Elastic properties and electronic structures of antiperovskite-type InNCo$_{3}$ and InNNi$_{3}$ Z. F. Hou Department of Physics, Fudan University, Shanghai, 200433, P. R. China We have performed the first-principles calculations to study the elasticity, electronic structure, and magnetism of InNCo$_{3}$ and InNNi$_{3}$. The independent elastic constants are derived from the second derivative of total energy as a function of strain, and the elastic modulus are predicted according to the Voigt-Reuss-Hill approximation. Our calculations show that the bulk modulus of InNCo$_{3}$ is slightly larger than that of InNNi$_{3}$ due to a smaller lattice constant for InNCo$_{3}$. For InNCo$_{3}$ the ferromagnetic state is energetically preferable to the paramagnetic state, while the ground state of InNNi$_{3}$ is a stable paramagnetic (non-magnetic) state. This is due to the different strength of 2 p -3 d hybridization for the N-Co and N-Ni atoms in InNCo$_{3}$ and InNNi$_{3}$. 1 arXiv:1002.1124v1 [cond-mat.mtrl-sci] 5 Feb 2010 Abstract