Showing papers on "Interatomic potential published in 1999"
TL;DR: In this article, the authors propose a first principle computation of the thermodynamics of simple fragile glasses starting from the two body interatomic potentials, and use a small cage expansion, valid at low temperatures, which allows to compute the cage size, the specific heat, and the configurational entropy.
Abstract: We propose a first principle computation of the thermodynamics of simple fragile glasses starting from the two body interatomic potential.
A replica formulation translates this problem into that of a gas of interacting molecules, each molecule being built of $m$ atoms, and having a gyration radius (related to the cage size) which vanishes at zero temperature. We use a small cage expansion, valid at low temperatures, which allows to compute the cage size, the specific heat (which follows the Dulong and Petit law), and the configurational entropy.
277 citations
TL;DR: In this paper, a first-principle computation of the equilibrium thermodynamics of simple fragile glasses starting from the two-body interatomic potential was proposed, which allows to compute the cage size, the specific heat (which follows the Dulong and Petit law), and configurational entropy.
Abstract: We propose a first-principle computation of the equilibrium thermodynamics of simple fragile glasses starting from the two-body interatomic potential. A replica formulation translates this problem into that of a gas of interacting molecules, each molecule being built of m atoms, and having a gyration radius (related to the cage size) which vanishes at zero temperature. We use a small cage expansion, valid at low temperatures, which allows to compute the cage size, the specific heat (which follows the Dulong and Petit law), and the configurational entropy.
205 citations
TL;DR: In this article, a new Cu(I)−O interaction potential has been parameterized based on abinitio data which is compatible with ab initio-parametrized shell model potentials for zeolites.
Abstract: Siting and coordination of Cu+ ions in zeolite ZSM-5 have been studied by a combined quantum mechanics/interatomic potential function technique. A new Cu(I)–O interaction potential has been parameterized based on abinitio data which is compatible with abinitio-parametrized shell model potentials for zeolites. Several different sites of Cu+ inside ZSM-5 have been found. The structure of the site and the coordination of the Cu+ ion depend on the T-site where the Si atom is replaced by an Al atom. If Al is at the edge of the main and sinusoidal channels the Cu+ ion prefers to occupy thc open space in the channel intersection and it is coordinated to two oxygen atoms of the AlO4 tetrahedron. The largest binding energy of Cu+ with ZSM-5 was found for Cu+ located inside a six-membered ring on the wall of the sinusoidal channel, where it can coordinate to three or four oxygen atoms of the zeolite framework. The Cu+ sites predicted are in accord with available experimental results.
201 citations
TL;DR: In this paper, a simple model of local shear transformation zones is developed in order to quantify the dependence of this sensitivity on the interparticle potential, and the model is applied to brittle fracture.
Abstract: Molecular-dynamics simulations of fracture in systems akin to metallic glasses are observed to undergo embrittlement due to a small change in interatomic potential. This change in fracture toughness, however, is not accompanied by a corresponding change in flow stress. Theories of brittle fracture proposed by Freund and Hutchinson indicate that strain rate sensitivity is the controlling physical parameter in these cases. A recent theory of viscoplasticity in this class of solids by Falk and Langer further suggests that the change in strain rate sensitivity corresponds to a change in the susceptibility of local shear transformation zones to applied shear stresses. A simple model of these zones is developed in order to quantify the dependence of this sensitivity on the interparticle potential.
176 citations
TL;DR: In this article, the surface properties of cubic CeO2 and ZrO2 were investigated at a periodic Hartee−Fock (HF) level, and the surface energy of both ceria and zirconia faces was calculated.
Abstract: In this paper, we present quantum mechanical (QM) calculations, at a periodic Hartee−Fock (HF) level, on the bulk and surface properties of cubic CeO2 and ZrO2. We have investigated the M−O bonding features, and established the high degree of ionicity of both materials, which is greater for CeO2 than ZrO2. The calculated values for the C11, C12, and C44 elastic constants, are in close agreement with experiment; an extended oxygen basis set, containing d-orbital polarization functions, is essential to model accurately the symmetry lowering during the C44 distortion. In the surface studies, we have calculated the surface energies of the {011} and {111} faces of both ceria and zirconia. QM results are compared with interatomic potential-based (IP) methods to assess the accuracy of the latter. We found that IP methods provide a correct estimate of the surface relaxations and the correct order of stability of the two faces examined, with the energy difference between the {011} and the {111} surfaces being appr...
138 citations
TL;DR: In this article, a novel interatomic potential energy function is proposed for condensed systems composed of silicon and oxygen atoms, from SiO2 to Si crystal, which is an extension of the Stillinger-Weber potential, originally designed for pure Si systems.
Abstract: A novel interatomic potential energy function is proposed for condensed systems composed of silicon and oxygen atoms, from SiO2 to Si crystal. The potential function is an extension of the Stillinger-Weber potential, which was originally designed for pure Si systems. All parameters in the potential function were determined based on ab initio molecular orbital calculations of small clusters. Without any adjustment to empirical data, the order of stability of five silica polymorphs is correctly reproduced. This potential realizes a large-scale modeling of SiO2/Si interface structures on average workstation computers.
129 citations
TL;DR: In this paper, a shell model is used to simulate the structural instabilities, dynamical properties, and phase transition sequence of BaTiO3 and the phase diagram as a function of temperature is obtained through constant-pressure molecular dynamics simulations.
Abstract: Interatomic potentials are determined in the framework of a shell model used to simulate the structural instabilities, dynamical properties, and phase transition sequence of BaTiO3. The model is developed from first-principles calculations by mapping the potential energy surface for various ferroelectric distortions. The parameters are obtained by performing a fit of interatomic potentials to this energy surface. Several zero-temperature properties of BaTiO3, which are of central importance, are correctly simulated in the framework of our model. The phase diagram as a function of temperature is obtained through constant-pressure molecular dynamics simulations, showing that the non-trivial phase transition sequence of BaTiO3 is correctly reproduced. The lattice parameters and expansion coefficients for the different phases are in good agreement with experimental data, while the theoretically determined transition temperatures tend to be too small.
120 citations
TL;DR: In this article, the atomic structures of the grain boundaries (GBs) in nanocrystalline materials and their effect on properties have been the subject of extensive discussion ever since the first ultrafine-grained polycrystals were synthesized by consolidation of small clusters formed via gas condensation.
102 citations
TL;DR: In this article, an interatomic potential was developed to investigate structural properties of hydrogenated amorphous silicon nitride and showed that hydrogen has a different chemical preference to bind to either nitrogen or silicon.
Abstract: We have developed an interatomic potential to investigate structural properties of hydrogenated amorphous silicon nitride. The interatomic potential used the Tersoff functional form to describe the Si–Si, Si–N, Si–H, N–H, and H–H interactions. The fitting parameters for all these interactions were found with a set of ab initio and experimental results of the silicon nitride crystalline phase, and of molecules involving hydrogen. We investigated the structural properties of unhydrogenated and hydrogenated amorphous silicon nitride through Monte Carlo simulations. The results show that depending on the nitrogen content, hydrogen has a different chemical preference to bind to either nitrogen or silicon, which is corroborated by experimental findings. Besides, hydrogen incorporation reduced considerably the concentration of undercoordinated atoms in the material, and consequently the concentration of dangling bonds.
95 citations
TL;DR: In this paper, a Tersoff-type empirical interatomic potential energy function (PEF) for the Si-C-F system was developed for the first application of this potential, etching of a:Si by CF3+ using molecular dynamics simulations.
Abstract: The development of a Tersoff-type empirical interatomic potential energy function (PEF) for the Si–C–F system is reported As a first application of this potential, etching of a:Si by CF3+ using molecular dynamics (MD) simulations is demonstrated Aspects of CF3+ ion bombardment through a fluence of 4×1016 cm−2 are discussed, including overlayer composition and thickness, Si etch yields, and etch product distributions The formation of a 1-nm-thick steady-state SixCyFz overlayer occurs in the simulation, and this layer is an active participant in the etching of the underlying Si At an ion energy of 100 eV, a steady state the etch yield of Si is predicted to be 006±001 Si/ion A comparison of the simulation findings and experimental results from the literature leads to the conclusion that the new PEF performs well in qualitatively modeling the atomic-scale processes involved in CF3+ ion beam etching of Si Simulations of this kind yield insight into fluorocarbon etch mechanisms, and ultimately will result in phenomenological models of etching by fluorocarbon plasmas
90 citations
TL;DR: In this article, the sliding and migration of [1 1 0] symmetric tilt grain boundaries (STGB) in aluminum, under both applied displacement and force conditions were studied.
Abstract: Interatomic potentials using Embedded Atom Method (EAM) are used in conjunction with molecular statics and dynamics calculations to study the sliding and migration of [1 1 0] symmetric tilt grain boundaries (STGB) in aluminum, under both applied displacement and force conditions. For equilibrium grain boundaries (without applied displacements and forces), three low energy configurations (corresponding to three twin structures) are found in the [1 1 0] STGB structures when grain boundary energies at 0 K are computed as a function of grain misorientation angle. “Pure” grain boundary sliding (GBS) without migration is simulated by applying external displacement. When forces are applied, the energy barriers are reduced consequent to the fact that grain boundary sliding of STGB is always coupled with migration. The propensity for “pure” GBS is evaluated by computing the energy associated with incremental equilibrium configurations during the sliding process and compared to the case when sliding is accompanied by migration. The magnitude of the energy barriers is found to be much higher in “pure” GBS than when migration accompanies sliding. Relations between the applied force, internal stress field, and displacement field are established and the role of grain boundary structure on the deformation process are examined. It is found that the GBS displacement is proportional to applied force, GB energy, and time.
TL;DR: An embedded atom model (EAM) interatomic potential that reproduces room temperature elastic behavior for α-Zr is developed in this article, which predicts a self-interstitial relaxation volume consistent with the relatively low measured value.
TL;DR: In this article, an interatomic potential model has been developed for molecular-dynamics simulations of rutile, in which atomic charges vary dynamically according to the generalized electronegativity equalization principle.
Abstract: An interatomic potential model has been developed for molecular-dynamics simulations of TiO2 (rutile) based on the formalism of Streitz and Mintmire [J. Adhes. Sci. Technol. 8, 853 (1994)], in which atomic charges vary dynamically according to the generalized electronegativity equalization principle. The present model potential reproduces the vibrational density of states, the pressure-dependent static dielectric constants, the melting temperature, and the surface relaxation of the rutile crystal, as well as the cohesive energy, the lattice constants, and the elastic moduli. We find the physical properties of rutile are significantly affected by dynamic charge transfer between Ti and O atoms. The potential allows us to perform atomistic simulations on nanostructured TiO2 with various kinds of interfaces (surfaces, grain boundaries, dislocations, etc.).
TL;DR: In this paper, a detailed study of Shockley partials in Pd is presented, using a full-scale atomistic simulation of the structure and energetics of the dislocation motion.
TL;DR: In this paper, a computationally efficient classical many-body potential designed to model the Al-Al interaction in a wide range of bonding geometries is discussed, which yields results in excellent agreement with experiment and ab initio calculations for a number of bulk and surface properties, among others for surface and step formation energies, and self-diffusion barriers.
Abstract: We discuss a computationally efficient classical many-body potential designed to model the Al-Al interaction in a wide range of bonding geometries. We show that the potential yields results in excellent agreement with experiment and ab initio calculations for a number of bulk and surface properties, among others for surface and step formation energies, and self-diffusion barriers. As an application, free-energy calculations are performed for the Al (100) surface by Monte Carlo thermodynamic integration and the quasiharmonic approximation. Comparison of the latter approximation with the reference Monte Carlo results provides information on its range of applicability to surface problems at high temperatures.
TL;DR: In this paper, it was shown that neural networks can be used to fit a two-element many-body potential function, and the system chosen is the C-H combination for which a manybody potential formulation due to Brenner exists.
Abstract: It is shown that neural networks can be used to fit a two-element many-body potential function. The system chosen is the C-H combination for which a many-body potential formulation due to Brenner exists. Comparison between this potential and the neural network indicates good agreement with both structure and energetics of the small C-H clusters and bulk carbon. However, because of the networks complicated structure, molecular dynamics simulations run at about a factor of 60-80% slower than with the Brenner many-body formalism.
TL;DR: In this article, a cubic-anvil-type apparatus (MAX90) with synchrotron radiation from the Photon Factory, Tsukuba, Japan was used to measure the X-ray absorption fine-structure (EXAFS) spectra near the Ge K-edge in diamond and white-tin-type Ge under high temperature and high pressure.
Abstract: Extended X-ray absorption fine-structure (EXAFS) spectra near the Ge K-edge in diamond- and white-tin-type Ge under high temperature and high pressure were measured using a cubic-anvil-type apparatus (MAX90) with synchrotron radiation from the Photon Factory, Tsukuba, Japan. Pressure values up to 10.6 GPa were estimated on the basis of the isothermal equation of state of the diamond-type Ge within an accuracy of 0.4 GPa. Pressures for the same cell assembly were also determined by X-ray diffraction experiment using the NaCl scale. The diamond-type Ge is of great advantage to the pressure calibrant of EXAFS measurements at elevated temperature because a harmonic approximation can be applied up to 900 K. By the phase transition from diamond- to white-tin-type phases, with an increase in coordination number, Ge—Ge distances increase. A sixfold-coordinated Ge atom in the white-tin-type structure has crystallographically non-equivalent two kinds of nearest-neighbour distances [2.530 (8) A and 2.697 (8) A at 12.8 GPa]. The harmonic effective interatomic potential, V(u) = 1/2αu2, was evaluated from the contribution to the thermal vibration, where u is the deviation of the bond distance from the location of the potential minimum. The potential coefficient, α, at 0.1 MPa is essentially temperature independent and is 9.06 eV A−2. At 9 GPa the potential coefficient is 9.71 eV A−2. The effective interatomic potential is influenced not only by pressure but also by changes in coordination number. The high-pressure white-tin-type phase has a broader potential and a relatively larger mean square amplitude of vibration than the diamond-type phase.
TL;DR: In this article, a single-crystal SrZrO3 with perovskite-type structure was grown by a floating-zone method and the polarized Raman scattering spectra were measured at room temperature.
Abstract: Single-crystal SrZrO3 with perovskite-type structure was grown by a floating-zone method. The polarized Raman scattering spectra were measured at room temperature. The observed Raman spectra were interpreted on the basis of a factor group analysis for the group D2h. Although 24 Raman active modes were expected, 15 bands were observed and the mode assignments were made by using D2h symmetry. Vibrational mode frequencies calculated using a rigid-ion model were helpful for the assignment of B1g and B3g modes and the interatomic potentials were estimated.
TL;DR: In this article, the structure and properties of vacancy loops and stacking-fault tetrahedra in copper have been studied by computer simulation using a long-range pair interatomic potential (LRPP), obtained from the generalized pseudopotential theory, and a many-body potential (MBP) of Finnis-Sinclair type.
Abstract: The structure and properties of vacancy loops (VIs) and stacking-fault tetrahedra (SFTs) in copper have been studied by computer simulation using a long-range pair interatomic potential (LRPP), obtained from the generalized pseudopotential theory, and a many-body potential (MBP) of Finnis-Sinclair type. The results obtained for these different potentials are qualitatively different. Thus, for the LRPP, significant atomic relaxation is observed for all defects. Triangular vacancy platelets relax into regular SFTs, and small hexagonal clusters form Frank loops, whereas large hexagonal clusters (containing more than 37 vacancies) can dissociate into six truncated SFTs with the side equal to the [110] side of the hexagon. Similar features are observed after the relaxation of circular loops. For the MBP, on the other hand, none of the hexagonal, circular and triangular planar vacancy platelets relax into a VL or SFT but remain almost unrelaxed 'holes', with a relative stability which is weakly dependent on the shape. The results obtained are compared with experiment and the results of other computer simulations, and the differences stemming from the use of different interatomic potentials and different simulation methods are discussed.
TL;DR: In this paper, the Brenner hydrocarbon potential was extended to include interactions with silicon and β-SiC. The new potential gives an excellent description of small Si m H n molecules and radicals.
Abstract: The Brenner hydrocarbon potential was extended recently to include interactions with silicon. This extended Brenner potential has now been improved by the fitting of bond order correction terms, and the introduction of an adjustable parameter into the angular function. The new potential gives an excellent description of small Si m H n molecules and radicals. Its treatment of the low index surfaces of silicon and β-SiC is also significantly improved, although the recently proposed non-dimerized structure for the silicon terminated (001) surface of β-SiC is not described properly. Calculations of the chemisorption of C2H2 and CH3 onto the (001) surfaces of silicon and β-SiC using this improved potential are reported. Also presented are some initial results of molecular dynamics simulations of the Si(111) 7 × 7:CH3 and hydrogenated Si(001) 2 × 1:C2H2 chemisorption systems.
01 Jun 1999-Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms
TL;DR: Applications of two modern artificial intelligence techniques, genetic algorithms and neural networks to computer simulations are reported and it is shown that the GA are very useful tools for determining the minimum energy structures of clusters of atoms described by interatomic potential functions.
Abstract: Applications of two modern artificial intelligence (AI) techniques, genetic algorithms (GA) and neural networks (NN) to computer simulations are reported. It is shown that the GA are very useful tools for determining the minimum energy structures of clusters of atoms described by interatomic potential functions and generally outperform other optimisation methods for this task. A number of applications are given including covalent, and close packed structures of single or multi-component atomic species. It is also shown that (many body) interatomic potential functions for multi-component systems can be derived by training a specially constructed NN on a variety of structural data.
TL;DR: In this article, an interatomic potential has been developed to describe the dynamics of Si/Cl systems, with particular relevance to reactive ion etching of Si by energetic Cl ions.
Abstract: An interatomic potential has been developed to describe the dynamics of Si/Cl systems, with particular relevance to reactive ion etching of Si by energetic Cl ions. We have modified the Stillinger–Weber (SW) potential of Feil et al. by adding two new terms: (1) an embedding term that corrects for the variation in Si–Cl bond strength as a function of the number of neighbors, and (2) a four-body term to describe the variation of the Si–Si bond strength as a function of the number of neighbors of each Si atom and the atom types (a bond order correction). Calculated Si etch rates obtained from molecular dynamics simulations using the new potential are in better agreement with recent experimental results than those obtained with the unmodified potential. Predictions of the stoichiometry of the etch products are also markedly different between the two potentials.
TL;DR: In this paper, the potential energy curves for the Na+-Rg (Rg = He, Ne and Ar) cationic complexes were calculated at the CCSD(T)/aug-cc-pVQZ level of theory, with correction for basis set superposition error being performed point-by-point.
Abstract: Interatomic potential energy curves are presented for the Na+—Rg (Rg = He, Ne and Ar) cationic complexes. The curves are calculated at the CCSD(T)/aug-cc-pVQZ level of theory, with correction for basis set superposition error being performed point-by-point. Ninety-six different bond lengths are used in the generation of the curves. From the curves rovibrational energy levels are calculated. These, in turn, are used to calculate the heat of formation of the cationic complexes, both by calculating partition functions under the assumption of a rigid rotor, harmonic oscillator, and also explicitly using the calculated rovibrational energy levels. The long range region of each of the curves is used to derive the D 4 and D 6 parameters, the former being used to derive the static polarizability a 1 of each of the Rg atoms and the latter the first dispersion coefficients, C 6(Na+—Rg).
TL;DR: In this paper, the first experimental evidence for dissociation of grain boundary screw dislocations was presented for (001) low-angle twist boundaries in silicon, using a combination of high-resolution electron microscopy and the weak-beam technique of transmission electron microscope.
Abstract: The first experimental evidence for dissociation of grain boundary screw dislocations is presented for (001) low-angle twist boundaries in silicon. Using a combination of high-resolution electron microscopy and the weak-beam technique of transmission electron microscopy, it is found that the grainboundary screw dislocations (b = 1/2 ) can dissociate in the (111) plane into two 30o partials, forming an intrinsic stacking fault, as do lattice screw dislocations of the glide set. On dissociation one partial dislocation stands off the grain-boundary plane. Some segments of the grain-boundary screw dislocations, however, may remain undissociated. An atomic model for the undissociated screw dislocation core, as well as a mechanism of its transformation into cores of individual 30o partials upon dissociation, are proposed on the basis of classical molecular dynamics simulations with an empirical interatomic potential. The model enables an understanding of the results of electron microscopy investigations.
TL;DR: Two new techniques in X-ray absorption spectroscopy (XAS) have recently been developed which provide previously unobtainable information on supported noble metal catalysts.
Abstract: Two new techniques in X-ray absorption spectroscopy (XAS) have recently been developed which provide previously unobtainable information on supported noble metal catalysts. Atomic X-ray absorption fine structure (AXAFS) provides direct information on the average changes in interatomic potential of the metal particles induced by metal-support effects. Changes in the interatomic potential can now be directly related to changes in catalytic reactivity. Analysis of shape resonances near the X-ray absorption edge provides information on the changes in the nature of the bonding of adsorbates (like hydrogen) to the metal cluster as induced by the properties of the support. The strong decrease in activity of supported platinum clusters for neo-pentane hydrogenolysis with increasing alkalinity of the support can be ascribed to a decrease in ionization potential of the metal particles directly influenced by the alkalinity of the support.
TL;DR: In this paper, the authors propose a first principles computation of the thermodynamics of simple fragile glasses starting from the two-body interatomic potential, and use a small cage expansion, valid at low temperatures, which allows them to compute the cage size, the specific heat (which follows the Dulong-Petit law) and the configurational entropy.
Abstract: We propose a first principles computation of the thermodynamics of simple fragile glasses starting from the two-body interatomic potential. A replica formulation translates this problem into that of a gas of interacting molecules, each molecule being build of m atoms, and having a gyration radius (related to the cage size) which vanishes at zero temperature. We use a small cage expansion, valid at low temperatures, which allows us to compute the cage size, the specific heat (which follows the Dulong-Petit law) and the configurational entropy.
TL;DR: In this article, an algorithm for Monte Carlo simulation of sputtered atom transport during ion-plasma sputtering was developed, where the experimentally determined initial energy distribution, the influence of the background gas mixture and the real equipment geometry of the magnetron sputtering system were taken into account.
TL;DR: In this paper, the Schottky and Frenkel defect energies for the GaInAlN system were derived by fitting pair potential parameters to bulk material properties, such as lattice constants and elastic and dielectric constants.
Abstract: We present interatomic pair potential parameters derived for the GaInAlN system. Potentials are fitted to bulk material properties, such as lattice constants and elastic and dielectric constants, and are then employed to calculate Schottky and Frenkel defect energies in GaN, InN and AlN. Schottky defects are found to be lower in energy than Frenkel defects, suggesting that vacancies are more readily formed in the group-III nitrides. The formation energies of both Schottky and Frenkel defects in all the nitrides are found to depend on the size of the cation. Solution energies indicate that InN readily dissolves in both GaN and AlN, at least at low concentration.
TL;DR: In this paper, the effect of the material used for a tool on atomic scale indentation and cutting mechanisms of metal workpieces is described by means of molecular dynamics simulations, where the interatomic force between the tool and workpiece is assumed to be a two-body interatomic potential using parameters based on the ab-initio molecular orbital calculation for a(Cr, Ni)-(C, Si)6H9 atom cluster.
Abstract: This paper describes the effect of the material used for a tool on atomic scale indentation and cutting mechanisms of metal workpieces, by means of molecular dynamics simulations. The interatomic force between the tool and workpiece is assumed to be a two-body interatomic potential using parameters based on the ab-initio molecular orbital calculation for a(Cr, Ni)-(C, Si)6H9 atom cluster. Molecular dynamics simulated the atomic scale indentation and cutting process of the chromium and nickel workpieces using the diamond, silicon and diamond-like carbon(DLC) tools. The diamond and DLC tools formed the indentation mark. Young's modulus of the chromium and nickel in indentation simulations was larger than that in experiments. This was qualitatively explained by the effect of the surface energy for the workpiece on the elastic modulus. The machinability of the chromium and nickel with the diamond tool was better than that of the silicon tool in atomic scale cutting simulations. The depth of the cut for the workpieces in nano scale cutting experiments with AFM, was similar to that in atomic scale cutting by molecular dynamics simulations.
TL;DR: In this paper, the harmonic effective interatomic potential V(u)=\alpha{u}^2/2 was evaluated from the contribution to the thermal vibration, where u is the deviation of the bond distance from the location of the potential minimum.
Abstract: Extended X-ray absorption fine structure (EXAFS) spectra near the Si and Ge K-edge for SiO_2 and GeO_2 polymorphs were measured in transmission mode with synchrotron radiation at the Photon Factory, Tsukuba. The local structures and mean-square relative displacements were determined in \alpha-tridymite, \alpha-quartz and stishovite. In stishovite, Si is octahedrally coordinated and the four coplanar Si—O bonds [1.755 (8) A] are shorter than the other two axial bonds [1.813 (15) A]. The high-temperature phase tridymite [1.597 (3) A] has a smaller local bond distance than \alpha-quartz [1.618 (5) A]. The temperature variation of the local structural parameters for quartz-type GeO_2 (q-GeO_2) and rutile-type GeO_2 (r-GeO_2) have been determined in the temperature range 7–1000 K. The harmonic effective interatomic potential V(u)=\alpha{u}^2/2 was evaluated from the contribution to the thermal vibration, where u is the deviation of the bond distance from the location of the potential minimum. The potential coefficient \alpha for the Ge—O bond of the tetrahedron in q-GeO_2 is 24.6 eV A−2. The potential coefficients \alpha for the four coplanar Ge—O bonds and the two axial bonds of the octahedron in r-GeO_2 are 12.9 and 14.9 eV A−2, respectively. The potential coefficient \alpha for the second-nearest Ge—Ge distance in q-GeO_2 is 9.57 eV A−2. The potential coefficients \alpha for the second- and third-nearest Ge—Ge distances in r-GeO_2 are 11.6 and 7.18 eV A−2, respectively. The effective interatomic potential is largely influenced by the local structure, particularly by the coordination numbers. The phonon dispersion relations for q-GeO_2 and r-GeO_2 were estimated along [100] by calculating the dynamical matrix using the potential coefficients \alpha for the Ge—O and Ge—Ge motions. The quartz-type structure has a more complex structure with a wide gap between 103 and 141 meV and a highest energy of 149 meV, whereas the rutile-type structure has a continuous distribution and a highest energy of 126 meV.