LAUSR

Comparison of EOS properties such as lattice parameters, bulk modulus, etc calculated by density functional theory (DFT) with experiments is used, in general, to assess the precision reachable in computations, when using different codes and potentials. DFT calculations using a large number of codes and potentials by different groups, have reported excellent precision (0.02 Å) in the lattice parameters of 71 elements. It is of interest to study the precision levels reachable in compounds of hexagonal NiAs type crystal structure, in which a wide range of electrical conductivity and magnetic order are found to occur. In this study, lattice parameters for 42 intermetallic compounds of the NiAs type structure are determined from internal radii using the Atom Pair Bond method. These values are compared with the lattice parameters reported from the high throughput DFT computational techniques such as AFLOW and Materials Project compilations. Precision in lattice parameters obtainable in the three methods is assessed in comparison with those reported from the experiments. Selection of a set of compounds of same crystal structure brings out the role of differences in the electronic structure of elements involved. In the APB method, lattice parameters are obtained by the best-fit equations defined by radii change in a large number of compounds with a particular structure, and do not involve several approximations, unlike in DFT. It is interesting to see that the simple APB approach could estimate lattice parameters with accuracies comparable to DFT methods.