Xian-Ru Hu

First-principle study on some new spin-gapless semiconductors: The Zr-based quaternary Heusler alloys

Employing first-principle calculations, we have investigated electronic and magnetic properties of the Zr-based quaternary Heusler alloys: ZrCoVIn, ZrFeVGe, ZrCoFeP, ZrCoCrBe and ZrFeCrZ (Z = In and Ga). Our calculation results show that all the alloys are (or nearly) spin-gapless semiconductors. The Slater–Pauling behaviours of these alloys are discussed as well. The cohesion energy and formation energy of these alloys have also been discussed, and the results indicate the studied alloys are stable.

THE FRIEDMANN EQUATION IN MODIFIED ENTROPY-AREA RELATION FROM ENTROPY FORCE

According to the formal holographic principle, a modification to the assumption of holographic principle in Verlinders investigation of entropy force is obtained. A more precise relation between entropy and area in the holographic system is proposed. With the entropy corrections to the area-relation, we derivate Newtons laws and Einstein equation with a static spherically symmetric holographic screen. Furthermore, we derived the correction terms to the modified Friedmann equation of the FRW universe starting from the holographic principle and the Debye model.

Quantum Monte Carlo calculated potential energy curve for the helium dimer

We report on the results of both the diffusion quantum Monte Carlo (DMC) and reptation quantum Monte Carlo (RMC) methods on the potential energy curve of the helium dimer. We show that it is possible to obtain a highly accurate description of the helium dimer. An improved stochastic reconfiguration technique is employed to optimize the many-body wave function, which is the starting point for highly accurate simulations based on the DMC and RMC methods. We find that the results of these methods are in excellent agreement with the best theoretical results at short range, especially the recently developed RMC method, yield particularly accurate results with reduced statistical error, which gives very excellent agreement across the whole potential curve. For the equilibrium internuclear distance of 5.6 bohrs, the calculated total energy with RMC method is -5.807 483 599+/-0.000 000 016 hartree and the corresponding well depth is -11.003+/-0.005 K.

THE FRIEDMANN EQUATIONS IN DEFORMED HOŘAVA–LIFSHITZ GRAVITY AND DEBYE MODEL

Considering the results from Hořava–Lifshitz (HL) theory, a more precise relation between the number of bits and area in the holographic system is proposed. With this corrected relation and Debye model, two modified Friedmann equations are derived from the Hawking temperature and the Unruh temperature separately in entropic force. These equations could be better in describing the whole evolution of the Universe.

The Klein-Gordon Equation in Machian Model

The non-local Machian model is regarded as an alternative theory of gravitation which states that all particles in the Universe as a ‘gravitationally entangled’ statistical ensemble. It is shown that the Klein-Gordon equation can be derived within this Machian model of the universe. The crucial point of the derivation is the activity of the Machian energy background field which causing a fluctuation about the average momentum of a particle, the non-locality problem in quantum theory is addressed in this framework.

First-Principle Study on Compensated Half Metallic Double Perovskite Compound Ba2PrVO6

The first-principle study on double perovskite compound Ba2PrVO6 has been presented in this paper. By analysing band structures and integrated density of states, it is found that Ba2PrVO6 is ferromagnetic metallic within LSDA and compensated half metallic whithin LSDA + U. According to the total and partial density of states, the anti-ferromagnetism of Ba2PrVO6 is originated from the spin down state Pr 4+ (4f−2) and the spin up hybridized state between the partially filled t2g state of V and the partially filled triple-degeneration state 4f−1, 4f+1, 4f+3 of Pr. We have investigated the magnetic evaluation of Ba2PrVO6 through fixed spin moment calculations, and the results indicate that the compensated half-metallic state is the ground state. The thermodynamic properties of Ba2PrVO6 are also studied by employing the quasi-harmonic Debye model.