Ion-ion and electron-ion correlations in liquid metallic sodium calculated from the nucleus-electron model

Abstract

On the basis of the density-functional theory with lhe use of the hyperneltedchain approximation, a set of integral equations for the ion-ion and electronion radial distribution functions (RDFs) have teen derived lor a liquid metal as a nucleus-electron mixture; its liquid and elecmnic swctures can be determined f" the atomic number 2,. This formulation is applied 10 liquid metallic sodium at temperature 100 V, these integral equations are solved in a self-consistent manner to obtain the ion-ion and eleclron-ion RDFS, the electron-density distribution of a pseudoatom p(r), and the effective interatomic potential & ( r ) at the Same time. m e ion-ion S~NC~UK factor of Na at 100 "$ thus calculated, show an unllent agreement with the experiment as well ar the ion-ion RDF, the effective interammic potential velf ( r ) giving this ion-ion RDF indicates a quite similar behaviour to that utracted from the measured swcture factor by Reatto a d, espeeialfy near the repulsiveare region. However, the elenmn-ion RDF and lhe pseudoatom-electron density p(r), obtained recenlly f " lhe difference beween structure factors ftom x-ray and neutron experiments, show large deviations from lhe calculated ones; this means lhal lo utracl lhese quantities the experiment should be performed in a more precise manner. For comparison, an effective interatomic potential B mnstrueted by the use of the Ashcroft pseudopotential with a mre radius 0.905 A, which )ields almost lhe Same electron-ion RDF and the Same screening charge p(r) ucept near the mre region in addition to the ionion RDF as obtained by the full selfmnsistenl method, the Ashcroft pseudopotential is shown IQ be appropriate in veating liquid Na in mntrast with liquid ti. where it is totally invalid.

Structure factor and electronic structure of compressed liquid rubidium

“…Up to now, we have applied this approach to liquid metallic hydrogen, 1 lithium, 3 sodium, 4 potassium, 5 and aluminum 6 obtaining ion-ion structure factors in excellent agreement with experiments. Since a liquid metal can be considered as a very special type of a high-density plasma, we can expect from the successful application of the QHNC method to liquid metals that this approach is able to provide accurate results for a plasma.…”

“…9 The NPA method can be derived from the QHNC theory with use of additional approximations; 10 the fundamental one is that the ion-ion correlation is approximated by the step function in the determination of the pseudopotential. This model was called in our approach the jellium-vacancy model 4 and was used to obtain an accurate initial guess for effective ion-ion interactions in the iteration solving the QHNC equation.…”

Ion-electron correlations in liquid metals from orbital-freeab initiomolecular dynamics

“…1 Very similar behavior has been predicted by means of the quantal hypernetted chain theory. 6,7 The consistent shape of the screening density in reciprocal space ͑Fig. 6͒ for Na, Mg, and Al, enables us to interpret the evolution of the ion-electron structure factor S Ie (k) ͑Fig.…”

Static ion structure factor for dense plasmas: Semi-classical and ab initio calculations

“…For instance, the neutral pseudoatom approach [13][14][15][16][17][18] has successfully been applied to calculate, e.g., equation of state data, structural and transport properties by combining density functional theory (DFT) for the electrons with appropriate ion structure calculation, usually by applying the hypernetted chain (HNC) scheme. A quantum HNC version (QHNC) for nucleus-electron mixtures has been developed and applied to liquid metals [19][20][21][22][23] as well as to partially ionized plasmas [24]. Ab initio simulations have already been used to determine the microscopic state of WDM and to construct appropriate ionic structure models [25,26] for the evaluation of X-ray scattering experiments.…”