SYSTEM =  Au compounds

Electronic strcutre

  PREC   = accurate

  ENCUT  = 1000 eV

  LREAL  = auto real space projections

  AMIX   = 0.5

  NBANDS = 180

  NELECT = 215  

#  RWIGS  = 1.05 1.05

 GGA = PE     #  PE Perdew-Burke-Ernzerhof (only VASP.4.5 and older)

  LORBIT = 11  

   # 11 RWIGS line in INCAR ：not read；files written： DOSCAR and PROCAR file with phase factors

#  NPAR   = 1

Ionic Relaxation

  NSW    = 99    number of steps for IOM

  IBRION = 2

  ISIF   = 2

  PSTRESS= 3000

DOS related values:

  ISMEAR =    0  ; SIGMA = 0.05

  EMIN   =   -15 ;  EMAX = 35

  NEDOS  = 1001

#

EMIN = real number (minimum energy for evaluation of DOS)

EMAX = real number (maximum energy for evaluation of DOS)

NEDOS= integer (number of grid points in DOS)

Hydride electrides:

An electride [电子化合物]is an ionic compound in which an electron is the anion【电子是阴离子】.^[1] Solutions of alkali metals in ammonia are electride salts.^[2] In the case of sodium, these blue solutions consist of [Na(NH₃)₆]⁺ and solvated electrons:

Na + 6 NH₃ → [Na(NH₃)₆]⁺,e⁻

The cation [Na(NH₃)₆]⁺ is an octahedralcoordination complex.

文献学习：

Hydride-Based Electride Material, LnH2 (Ln = La, Ce, or Y)

ABSTRACT:

In view of the strong electron-donating nature of
H− and extensive vacancy formation in metals by hydrogen
insertion, a series of LnH2+x (Ln = La, Ce, or Y) compounds with
fluorite-type structures were verified to be the first hydride-based
electride, where itinerant electrons populating the cage are
surrounded by H− anions.

The electron transfer into the cage
probably originates from Ln−cage covalent interaction.【可能起源于镧系金属cage的共价作用】

To the
best of our knowledge, anion-rich electrides are extremely rare,
and a key requirement for their formation is that the cage site is
not occupied by lone pair electrons of the adjacent ions.  

【cage site 不能被含有孤对电子的邻近离子占据】

In the
case of LnH2, the cage site is surrounded by eight H− anions with
isotopic electronic character caused by the lack of mixing of H p-orbital character.

Notably, Ru-loaded LnH2+x electride powders
synthesized by hydrogen embrittlement (Ln = La or Ce) were found to work as efficient catalysts for ammonia synthesis at
ambient pressure, without showing serious signs of hydrogen poisoning.  【合成氨催化剂Ru-LnH2+x】

There are several possible origins of the observed high
catalytic activity in the hydride promotors: the small work function of LnH2+x derived from the covalent interaction between Ln
cation and the H− σ donor, and the formation of Ln nitride during 【镧系金属氮化物】catalytic reaction.

Here, we report on the design concept of less-noble-metal based electride materials, which can easily produce fine powders by a simple treatment.

    We choose to work with lanthanide metals, which have low WFs(work functions

功函数) (La, Ce, and Y have WFs of 3.5, 2.9, and 3.1 eV, respectively5), and their properties are modified by the utilization of hydrogen.

The hydrogen ion has several unique characteristics:

its charge can change between +1, 0, and −1;

its size is rather flexible, even in the same charge state;

H− is a strong σ donor, comparable to CN−; it has an isotropic electronic structure because of the lack of energetically available p states; it exhibits fast diffusion in metals/alloys; and so on.6

Consequently, hydrogen behaves as a donor for positive metals, including Ln; therefore, the highest occupied energy level of Ln 5d/4f is raised by the covalent interaction with H−, leading to a decrease in WF (Scheme 1).

  Furthermore, facile synthesis of fine powders employing hydrogen embrittlement may be anticipated. We found that LnH₂ (Ln = La or Ce) with a fluorite-ype structure is a new electride material having itinerant electrons populating a cage surrounded by eight H− anions, although this compound is already a well-known material. Furthermore, Ru-loaded LnH₂ powders are reported to be efficient catalysts for ammonia synthesis at ambient pressure.

The electronic structure shows a metallic nature owing to a Fermi surface (FS) originating from La 5d eg. Notably, the bonding parts of the two H 1s orbitals (−2.4 to −6.2 eV) are deeper than those of the La 6s/5d/4f orbitals, suggesting that Ht serves as an anion【阴离子】.

The total bandwidth related to the occupied H 1s states is ∼3.8 eV.

The 6s and part of the 5d orbitals of La are destabilized through covalent interaction with the Ht− σ donor, resulting in the decrease of WF, as indicated in Scheme 1. Again, we can find important orbital interactions along the Γ to X line. La 5d t2g−Ht 1s σ interaction is possible at the X point (bonding, −4.7 eV). The inserted Ht only removes a La t2g band from the  energy region near EF by destabilization via covalent interaction, while a La 5d eg band remains near EF because it has no interaction at the X point (−1.5 eV) due to the restriction of orbital symmetry. Figure 3a shows the electron  density map of LaH2 in the energy region from −1.5 eV to EF.

  Surprisingly, conduction electrons populate the cage site and show strong anisotropic shape into the six neighboring La ions. As seen in Figure 3b, the (110) plane obviously contains a large contribution from La 5dz2 (eg, red part). Thus, we may regard LaH2V as an inorganic electride in which the electrons reside in the center of the Ht8 cube. However, the electrides reported to