Three-body Interaction Potential Research Articles

High Pressure Phase Transition and Allied Behavior οf Samarium Compounds

(Received March 6, 2012; revised version February 16, 2013; in nal form February 26, 2013) A theoretical study of the phase transition of samarium monochalcogenides using three-body interaction potential model is carried out at high pressure. The three-body interaction potential includes long range Coulombic, three-body interaction forces and short range overlap repulsive forces operative up to next nearest neighbor ions. We have investigated phase transition pressures, volume collapses, elastic behavior, stability criteria and various thermo physical properties at various high pressure. The results found are well suited with available experimental data. In this paper third order elastic constants are also reported for the rst time which helps in understanding the nature of interionic forces in ionic solids which paved the experimentalist to work in speci c direction.

High Pressure Phase Transition Phenomena in CeS and LaS

In present study we have investigated the high pressure phase transition pressures, volume collapses, elastic and thermo-physical properties of cerium and lanthanum sulphides using the three body interaction potential (TBIP) approach. The CeS and LaS belong to the wide class of binary rare-earth monochalcogenides which crystallize in NaCl-type structure and undergo a transformation into CsCl-type structure under pressure. The values of phase transition pressure and associated volume collapse estimated by us are found to be well suited with experimental values.

Interaction potential for aluminum nitride: A molecular dynamics study of mechanical and thermal properties of crystalline and amorphous aluminum nitride

An effective interatomic interaction potential for AlN is proposed. The potential consists of two-body and three-body covalent interactions. The two-body potential includes steric repulsions due to atomic sizes, Coulomb interactions resulting from charge transfer between atoms, charge-induced dipole-interactions due to the electronic polarizability of ions, and induced dipole–dipole (van der Waals) interactions. The covalent characters of the Al–N–Al and N–Al–N bonds are described by the three-body potential. The proposed three-body interaction potential is a modification of the Stillinger–Weber form proposed to describe Si. Using the molecular dynamics method, the interaction potential is used to study structural, elastic, and dynamical properties of crystalline and amorphous states of AlN for several densities and temperatures. The structural energy for wurtzite (2H) structure has the lowest energy, followed zinc-blende and rock-salt (RS) structures. The pressure for the structural transformation from wurtzite-to-RS from the common tangent is found to be 24 GPa. For AlN in the wurtzite phase, our computed elastic constants (C11, C12, C13, C33, C44, and C66), melting temperature, vibrational density-of-states, and specific heat agree well with the experiments. Predictions are made for the elastic constant as a function of density for the crystalline and amorphous phase. Structural correlations, such as pair distribution function and neutron and x-ray static structure factors are calculated for the amorphous and liquid state.

Pressure-induced phase transition phenomena in NpSe and NpTe

A three-body interaction potential (TBIP) has been formulated by incorporating the effects of long-range coulomb interaction, three-body interaction and short-range repulsive interactions effective up to second neighbor ions. The three-body interactions arise from the electron-shell deformation when the nearest-neighbor overlaps. This TBIP has been employed for detailed studies of pressure-induced phase transition and high-pressure behavior of NpSe and NpTe. The model has yielded fairly good description of the cohesive energy, compressibility, molecular force constant, reststralhlen frequency and Debye temperature in case of these actinide monochalcogenides.

Weak interaction limit for nuclear matter and the time-dependent Hartree-Fock equation

We consider an effective model of nuclear matter including spin and isospin degrees of freedom, described by an N-body Hamiltonian with suitably renormalized two-body and three-body interaction potentials. We show that the corresponding mean-field theory (the time-dependent Hartree-Fock approximation) is “exact” as N tends to infinity.

Feshbach resonances in ultracold atom-molecule collisions

We investigate the presence of Feshbach resonances in ultracold alkali-dialkali reactive collisions. A potential-energy surface of ${\text{Na}}_{3}$ in the lowest quartet state is constructed and used in quantum scattering calculations. An analysis of scattering features is performed through a systematic variation in the nonadditive three-body interaction potential. Our results should provide useful information for interpreting future atom-molecule collision experiments.

Molecular dynamic simulations of some thermodynamic properties of mixtures of argon with neon, krypton, and xenon using two-body and three-body interaction potentials

Molecular dynamics (MD) has been performed to compute the pressure and internal energy of binary mixtures of argon–neon, argon–krypton, and argon–xenon at different temperatures and compositions using two-body Hartree–Fock dispersion-like (HFD-like), total (two-body + three-body) HFD-like, and Lennard–Jones (LJ) potentials. The results are in a good overall agreement with the experimental data. To elucidate the role of three-body interactions on the thermodynamic properties of the studied mixtures, we have incorporated Wang and Sadus method into MD simulations performed using density-dependent two-body HFD-like potentials. Much better results for pressure have been obtained at high densities using the effective LJ potential. For the second virial coefficient, the HFD-like potential is a better choice. Since a little attention has been paid to the qualitative analysis of RDF in the liquid mixtures so far, we have also analyzed the variation of radial distribution function (RDF) of the mixtures with density and composition.

Pressure-induced phase transition and stability of EuO and EuS with NaCl structure

We have predicted the phase transition pressures and corresponding relative volume changes of EuO and EuS having NaCl-type structure under high pressure using three-body interaction potential (TBIP) approach. In addition, the conditions for relative stability in terms of modified Born criterion has been checked. Our calculated results of phase transitions, volume collapses and elastic behaviour of these compounds are found to be close to the experimental results. This shows that the inclusion of three-body interaction effects makes the present model suitable for high pressure studies.

Structural and elastic properties of barium chalcogenides (BaX, X=O, Se, Te) under high pressure

Abstract In the present paper we have investigated the high-pressure, structural phase transition of Barium chalcogenides (BaO, BaSe and BaTe) using a three-body interaction potential (MTBIP) approach, modified by incorporating covalency effects. Phase transition pressures are associated with a sudden collapse in volume. The phase transition pressures and associated volume collapses obtained from TBIP show a reasonably good agreement with experimental data. Here, the transition pressure, NaCl-CsCl structure increases with decreasing cation-to-anion radii ratio. In addition, the elastic constants and their combinations with pressure are also reported. It is found that TBP incorporating a covalency effect may predict the phase transition pressure, the elastic constants and the pressure derivatives of other chalcogenides as well.

Theoretical analysis of pressure-induced phase transition of EuS and EuSe including the role of temperature

Abstract An effective interaction potential is developed to study the high-pressure phase transition of EuS and EuSe having NaCl-type (B 1 ) structure at room temperature. The three-body interaction potential (TBIP) includes long-range Coulombic, three-body interaction forces, short-range overlap repulsive forces operative up to next nearest neighbor ions, van der Walls interactions and zero point energy effects. We are incorporating temperature effects in three body potential model for the first time and this has made TBIP more realistic. Earlier theoretical studies of phase transition with TBIP model have been carried by assuming the equilibrium at 0 K instead of room temperature. We have theoretically investigated phase transition pressures, volume collapses and elastic behavior of EuS and EuSe at room temperature and found results well suited with available experimental data. This shows that the inclusion of temperature effects in TBIP makes the present model suitable for theoretical high-pressure studies.

Water trimer torsional spectrum from accurate ab initio and semiempirical potentials

The torsional levels of (H2O)3 and (D2O)3 were calculated in a restricted dimensionality (three-dimensional) model with several recently proposed water potentials. Comparison with the experimental data provides a critical test, not only of the pair interactions that have already been probed on the water dimer spectra, but also of the nonadditive three-body contributions to the potential. The purely ab initio CC-pol and HBB potentials that were previously shown to yield very accurate water dimer levels, also reproduce the trimer levels well when supplemented with an appropriate three-body interaction potential. The TTM2.1 potential gives considerably less good agreement with experiment. Also the semiempirical VRT(ASP-W)III potential, fitted to the water dimer vibration-rotation-tunneling levels, gives substantial disagreement with the measured water trimer levels, which shows that the latter probe the potential for geometries other than those probed by the dimer spectrum. Although the three-body nonadditive interactions significantly increase the stability of the water trimer, their effect on the torsional energy barriers and vibration-tunneling frequencies is less significant.

Study of high-pressure phase transition of CeTe and EuTe through three-body interaction potential approach

The high pressure phase transition of lanthanum monotellurides having NaCl-type (B 1) structure have been studied using three-body interaction potential (TBIP) approach. The potential model consists of long-range Coulombic, three-body interaction forces, short-range overlap repulsive forces operative up to next nearest neighbor ions, van der Walls interactions and zero point energy effects. To understand the effect of pressure on elastic constant and their combinations, they have also been studied. The Born stability criterion was also found to be fulfiled in the present study. Our calculated results of phase transitions, volume collapses and elastic behavior of these monotellurides are found to be close to the experimental results. This shows that the inclusion of three-body interaction effects makes the present model suitable for high-pressure studies.

Development of a classical force field for the oxidized Si surface: Application to hydrophilic wafer bonding

We have developed a classical two- and three-body interaction potential to simulate the hydroxylated, natively oxidized Si surface in contact with water solutions, based on the combination and extension of the Stillinger-Weber potential and of a potential originally developed to simulate SiO(2) polymorphs. The potential parameters are chosen to reproduce the structure, charge distribution, tensile surface stress, and interactions with single water molecules of a natively oxidized Si surface model previously obtained by means of accurate density functional theory simulations. We have applied the potential to the case of hydrophilic silicon wafer bonding at room temperature, revealing maximum room temperature work of adhesion values for natively oxidized and amorphous silica surfaces of 97 and 90 mJm(2), respectively, at a water adsorption coverage of approximately 1 ML. The difference arises from the stronger interaction of the natively oxidized surface with liquid water, resulting in a higher heat of immersion (203 vs 166 mJm(2)), and may be explained in terms of the more pronounced water structuring close to the surface in alternating layers of larger and smaller densities with respect to the liquid bulk. The computed force-displacement bonding curves may be a useful input for cohesive zone models where both the topographic details of the surfaces and the dependence of the attractive force on the initial surface separation and wetting can be taken into account.

Interaction potential for silicon carbide: A molecular dynamics study of elastic constants and vibrational density of states for crystalline and amorphous silicon carbide

An effective interatomic interaction potential for SiC is proposed. The potential consists of two-body and three-body covalent interactions. The two-body potential includes steric repulsions due to atomic sizes, Coulomb interactions resulting from charge transfer between atoms, charge-induced dipole-interactions due to the electronic polarizability of ions, and induced dipole-dipole (van der Waals) interactions. The covalent characters of the Si–C–Si and C–Si–C bonds are described by the three-body potential. The proposed three-body interaction potential is a modification of the Stillinger-Weber form proposed to describe Si. Using the molecular dynamics method, the interaction potential is used to study structural, elastic, and dynamical properties of crystalline (3C), amorphous, and liquid states of SiC for several densities and temperatures. The structural energy for cubic (3C) structure has the lowest energy, followed by the wurtzite (2H) and rock-salt (RS) structures. The pressure for the structural transformation from 3C-to-RS from the common tangent is found to be 90 GPa. For 3C-SiC, our computed elastic constants (C11, C12, and C44), melting temperature, vibrational density-of-states, and specific heat agree well with the experiments. Predictions are made for the elastic constant as a function of density for the crystalline and amorphous phase. Structural correlations, such as pair distribution function and neutron and x-ray static structure factors are calculated for the amorphous and liquid state.

Phase transition in CeSe, EuSe and LaSe under high pressure

AbstractThe high pressure phase transition and elastic behavior of rare earth monoselenides (CeSe, EuSe and LaSe) which crystallize in a NaCl-structure have been investigated using the three body interaction potential (TBIP) approach. These interactions arise due to the electronshell deformation of the overlapping ions in crystals. The TBP model consists of a long range Coulomb, three body interactions and the short range overlap repulsive forces operative up to the second neighboring ions. The authors of this paper estimated the values of the phase transition pressure and the associated volume collapse to be closer than other calculations. Thus, the TBIP approach also promises to predict the phase transition pressure and pressure variations of elastic constants of lanthanide compounds.

Ab initio quantum mechanical charge field (QMCF) molecular dynamics: a QM/MM – MD procedure for accurate simulations of ions and complexes

A new formalism for quantum mechanical / molecular mechanical (QM/MM) dynamics of chemical species in solution has been developed, which does not require the construction of any other potential functions except those for solvent–solvent interactions, maintains all the advantages of large simulation boxes and ensures the accuracy of ab initio quantum mechanics for all forces acting in the chemically most relevant region. Interactions between solute and more distant solvent molecules are incorporated by a dynamically adjusted force field corresponding to the actual molecular configuration of the simulated system and charges derived from the electron distribution in the solvate. The new formalism has been tested with some examples of hydrated ions, for which accurate conventional ab initio QM/MM simulations have been previously performed, and the comparison shows equivalence and in some aspects superiority of the new method. As this simulation procedure does not require any tedious construction of two-and three-body interaction potentials inherent to conventional QM/MM approaches, it opens the straightforward access to ab initio molecular dynamics simulations of any kind of solutes, such as metal complexes and other composite species in solution.

Account of three-body interactions in the lattice dynamics method

The lattice dynamics method is extended with the account of three-body interaction potential in the harmonic approximation. Analytic expressions for the force constants and dynamical matrix elements are presented. Dynamical matrix element responsible for indirect interaction of atoms is single out. Modeling calculations of phonon spectra at the center of Brillouin zone for empty silicon clathrate structures Si 34 and Si 46 have been performed.

High pressure phase transition and variation of elastic constants of diluted magnetic semiconductors

AbstractA theoretical study of the high‐pressure phase transition and elastic behavior in diluted magnetic semiconductors Zn0.83Mn0.17Se, using a three‐body interaction (TBI) potential caused by the electron‐shell deformation of the overlapping ions is carried out. The estimated values of phase transition pressure and the vast volume discontinuity in pressure‐volume (PV) phase diagram indicate the structural phase transition from zincblende (B3) to rock salt (B1). The variation of second‐order elastic constants with pressure resembles that observed in some binary semiconductors. The inconsistency in the deduced value of pressure derivative of second order elastic constant with the available data is attributed to the fact that we derive expressions neglecting thermal effects and assuming the overlap repulsion significant only up to nearest neighbors. The vdW interaction is effective in obtaining the thermodynamical parameters such as Debye temperature, Gruneisen parameter, thermal expansion coefficient, compressibility as well phase stability in diluted magnetic semiconductors. It is revealed that TBI model has a promise to predict the phase transition pressure and the pressure variation of elastic constants of other semiconductors as well. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Molecular-dynamics simulation of Si 1− xGe x epitaxial growth on Si( [formula omitted

Molecular dynamics study of the Si 1− x Ge x epitaxial growth on Si(1 0 0) substrate utilizing the Stillinger–Weber two- and three-body interaction potentials was carried out. The Stranski–Krastanov growth mechanism of the Si 1− x Ge x strain layers on Si(1 0 0) was studied and compared with experiment results. The influence of different x on the epitaxial growth layers morphology was investigated. The structure properties of the Si 1− x Ge x layers were evaluated.

Study of Ge epitaxial growth on Si substrates by cluster beam deposition

Ge epitaxial layers with reasonable quality were grown on Si (1 1 1) substrates by cluster beam deposition (CBD) process. Molecular dynamics study of the low energy Ge clusters deposition process utilizing the Stillinger–Weber two- and three-body interaction potentials was carried out to compare the experimental results. Both experimental and simulation results prove that the substrate temperature plays a dominant role in the epitaxial growth of Ge films in CBD process. The influence mechanisms of temperature are discussed.