Pressure dependency of localization degree in heavy fermion CeIn3: A density functional theory analysis

Abstract

Two dramatic discrepancies between previous reliable experimental and ab initio DFT results are identified to occur at two different pressures in CeIn3, as discussed through the paper. We physically discuss sources of the phenomena and indicate how to select an appropriate functional for a given pressure. We show that these discrepancies are due to the inaccuracy of the DFT + U scheme with arbitrary Ueff and that hybrid functionals can provide better agreement with experimental data at zero pressure. The hybrid B3PW91 approach provides much better agreement with experimental data than the GGA + U. The DFT + U scheme proves to be rather unreliable since it yields completely unpredictable oscillations for the bulk modulus with increasing values of Ueff. Our B3PW91 results show that the best lattice parameter (bulk modulus) is obtained using a larger value of α parameter, 0.4 (0.3 or 0.2), than that of usually considered for the AFM phase. We find that for hybrid functionals, the amount of non-local exchange must first be calibrated before conclusions are drawn. Therefore, we first systematically optimize the α parameter and using it investigate the magnetic and electronic properties of the system. We present a theoretical interpretation of the experimental results and reproduce them satisfactorily.

Thermoelectric properties of heavy fermion CeRhIn5 using density functional theory combined with semiclassical Boltzmann theory

“…This implies that the localization degree of these electrons can be reduced by imposing pressure. Furthermore, we discussed in our recent work, 55 in agreement with previous works, 76 that the exchange–correlation energy of Ce-based compounds could not be satisfactorily described only by a single functional for every pressure. Therefore, for a specific pressure range an appropriate functional must be selected; band-correlated (band-like) functionals are more appropriate for low (high) pressures.…”

“…This difference conrms a more signicant effect of the localization degree than pressure in complete agreement with the result reported for CeIn 3 in our recent work. 55 This result can be reconrmed if we consider the fact that the degree of localization predicted by PBE-GGA is lower than those predicted by GGA+U and B3PW91. Keeping the latter fact in mind, we see in Table 1 that, in contrast to pressure, the bands data are substantially affected by the degree of 4f localization.…”

“…Therefore, for a specic pressure range an appropriate functional must be selected; band-correlated (band-like) functionals are more appropriate for low (high) pressures. 55 Thus, following this strategy, in addition to the band-correlated GGA+U and hybrid B3PW91 approaches, the band-like PBE-GGA functional is also used for the electronic structure investigation. Now, we can discuss the electronic structure of the system by considering the above points.…”

“…Our results also reveal that the effect of hydrostatic pressure on the thermoelectric parameters strongly depends on the considered degree of localization for 4f-Ce electrons, in accordance with our previous work. 55 The electronic structures of CeRhIn 5 , including its density of states (DOS) and band structure are also investigated in this study.…”

First principles study of structural, magnetic and electronic properties of CrAs

“…For completeness, we mention that a way to possibly improve the results of this paper could be the application of some hybrid functionals. Nevertheless, while some hybrid exchange functionals are not suitable to describe the metals, 29 the B3PW91 code has been demonstrated to give good results to describe the magnetic metals, 30 giving rise to a magnetization lower than that obtained by means of SGGA when low values of the mixing parameters are considered.…”