Very recently, we have used first-principles methods to calculate the zero-temperature phase diagram of all the 4d transition metals up to P 500GPa. Even though we used a very accurate implementation of density functional theory and the accurate exchange-correlation functional of Wu and Cohen, we found that solid-solid transition pressures were underestimated by 10GPa with respect to room-temperature measurements. Here, we report the dependence of the transition pressures on the choice of the exchange-correlation functional. We also perform first-principles calculations of the harmonic phonon frequencies of molybdenum and zirconium in different crystalline structures in order to extend the phase diagram to non-zero temperatures. We use the results to discuss the reasons for the earlier disagreements between calculated and experimental transition pressures.
Effect of the exchange-correlation energy and temperature on the generalized phase diagram of the 4d transition metals / Cazorla, C; Binnie, S; Alfe, D; Gillan, Mj. - In: HIGH PRESSURE RESEARCH. - ISSN 0895-7959. - 28:4(2008), pp. 449-453. [10.1080/08957950802506925]
Effect of the exchange-correlation energy and temperature on the generalized phase diagram of the 4d transition metals
Alfe D;
2008
Abstract
Very recently, we have used first-principles methods to calculate the zero-temperature phase diagram of all the 4d transition metals up to P 500GPa. Even though we used a very accurate implementation of density functional theory and the accurate exchange-correlation functional of Wu and Cohen, we found that solid-solid transition pressures were underestimated by 10GPa with respect to room-temperature measurements. Here, we report the dependence of the transition pressures on the choice of the exchange-correlation functional. We also perform first-principles calculations of the harmonic phonon frequencies of molybdenum and zirconium in different crystalline structures in order to extend the phase diagram to non-zero temperatures. We use the results to discuss the reasons for the earlier disagreements between calculated and experimental transition pressures.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.