First-principles investigation of the effect of pressure on CaFe$_2$As$_2$ and Pr-doped Ca$_{1-x}$Pr$_{x}$Fe$_ {2}$ As$_ {2}$*

In a recent study (arXiv:1310.3842), superconductivity has been observed at critical temperature ~51 K under pressure 1.9 GPa for rare-earth doped Ca$_{0.86}$Pr$_{0.14}$Fe$_2$As$_2$ which is the highest T$_c$ reported in the class of 1-2-2 iron-based superconductors. Motivated by this, we present density functional theory calculations on iron-based pnictide undoped CaFe$_2$As$_2$ and Pr-doped Ca$_{1-x}$Pr$_x$Fe$_2$As$_2$ ($x$=0.25 and 0.125). The calculations have been carried out using plane-waves and pseudopotential approach within generalized gradient approximation (GGA) and also within GGA+U in order to investigate the influence of correlation effects. The effect of pressure on crystal structure, magnetic order, and electronic structure are investigated for both undoped and Pr-doped structures for comparison and discussed with experimental findings.