Structural $\alpha$–$\gamma$ transition in iron within the GGA + DMFT method taking into account the rotational invariance of the Coulomb interaction

The structural $\alpha$–$\gamma$ transition in iron has been studied in the framework of the GGA + DMFT method using the generalized gradient approximation (GGA) and the dynamical mean field theory (DMFT). The impurity problem in the DMFT has been solved using the recently proposed method based on the Hirsch–Fye algorithm and approximately taking into account the rotational invariance of the Coulomb interaction. It has been shown that a decrease in the calculated Curie–Weiss temperature is accompanied by a decrease in the calculated $\alpha$–$\gamma$ transition temperature if one takes into account the rotational invariance of the Coulomb interaction. Moreover, the agreement between the calculated $\alpha$–$\gamma$ transition temperature and its experimental value is improved. The results obtained agree with the earlier proposed explanation of the mechanism of this transition, according to which its main driving force is the magnetic correlation energy.