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Del Rio BG, Pascual C, González LE, González DJ. Structure and dynamics of the liquid 3d transition metals near melting. An ab initio study. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:214005. [PMID: 31972549 DOI: 10.1088/1361-648x/ab6f16] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The static and dynamic properties of several bulk liquid 3d transition metals at thermodynamic conditions near their respective melting points have been evaluated by using ab initio molecular dynamics simulations. The calculated static structure factors show an asymmetric second peak followed by a more or less marked shoulder which points to a sizeable amount of icosahedral local order. Special attention is devoted to the analysis of the longitudinal and transverse current spectral functions and the corresponding dispersion of collective excitations. For some metals, we have found the existence of two branches of transverse collective excitations in the second pseudo-Brillouin zone. Finally, results are also reported for several transport coefficients.
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Affiliation(s)
- Beatriz G Del Rio
- Departamento de Física Teórica, Universidad de Valladolid, Valladolid, Spain
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del Rio BG, Dieterich JM, Carter EA. Globally-Optimized Local Pseudopotentials for (Orbital-Free) Density Functional Theory Simulations of Liquids and Solids. J Chem Theory Comput 2017; 13:3684-3695. [DOI: 10.1021/acs.jctc.7b00565] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Beatriz G. del Rio
- Departamento
de Física Teórica, Facultad de Ciencias, Universidad de Valladolid, 47002 Valladolid, Spain
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del Rio BG, González LE, González DJ. Ab initio study of several static and dynamic properties of bulk liquid Ni near melting. J Chem Phys 2017; 146:034501. [DOI: 10.1063/1.4973803] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- B. G. del Rio
- Departamento de Física Teórica, Universidad de Valladolid, 47011 Valladolid, Spain
| | - L. E. González
- Departamento de Física Teórica, Universidad de Valladolid, 47011 Valladolid, Spain
| | - D. J. González
- Departamento de Física Teórica, Universidad de Valladolid, 47011 Valladolid, Spain
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Marqués M, González LE, González DJ. Pressure-induced changes in structural and dynamic properties of liquid Fe close to the melting line. An ab initio study. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2016; 28:075101. [PMID: 26811899 DOI: 10.1088/0953-8984/28/7/075101] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The static and dynamic properties of liquid Fe at high pressure and temperature have been studied using an ab initio molecular dynamics method. We have focused on four thermodynamic states at pressures of 27, 42, 50 and 58 GPa for which x-ray scattering data are available. The calculated static structure shows very good agreement with the available experimental data, including an asymmetric second peak which becomes more marked with increasing pressure. The dynamical structure reveals the existence of propagating density fluctuations and the associated dispersion relation has also been determined. The relaxation mechanisms for the density fluctuations have been analyzed in terms of a model with two decay channels (fast and slow, respectively). We found that the thermal relaxation proceeds along the slow decaying channel whereas the fast one is that of the viscoelastic relaxation. The possible coupling between longitudinal and transverse excitation modes has been investigated by looking at specific signatures in two wavevector regions: the first one is located around the position of the main peak of the structure factor, qp, as suggested by the recently reported appearance of high frequency transverse waves in liquid Li under high pressures; the second region is around qp/2, as suggested by the recent finding of transverse acoustic modes in inelastic x-ray scattering intensities of liquid Fe at ambient pressure. Finally, results are also reported for several transport coefficients.
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Affiliation(s)
- Miriam Marqués
- Departamento de Física Teórica, Universidad de Valladolid, Valladolid, Spain
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Bryk T, Gorelli F, Ruocco G, Santoro M, Scopigno T. Collective excitations in soft-sphere fluids. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2014; 90:042301. [PMID: 25375488 DOI: 10.1103/physreve.90.042301] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2013] [Indexed: 06/04/2023]
Abstract
Despite that the thermodynamic distinction between a liquid and the corresponding gas ceases to exist at the critical point, it has been recently shown that reminiscence of gaslike and liquidlike behavior can be identified in the supercritical fluid region, encoded in the behavior of hypersonic waves dispersion. By using a combination of molecular dynamics simulations and calculations within the approach of generalized collective modes, we provide an accurate determination of the dispersion of longitudinal and transverse collective excitations in soft-sphere fluids. Specifically, we address the decreasing rigidity upon density reduction along an isothermal line, showing that the positive sound dispersion, an excess of sound velocity over the hydrodynamic limit typical for dense liquids, displays a nonmonotonic density dependence strictly correlated to that of thermal diffusivity and kinematic viscosity. This allows rationalizing recent observation parting the supercritical state based on the Widom line, i.e., the extension of the coexistence line. Remarkably, we show here that the extremals of transport properties such as thermal diffusivity and kinematic viscosity provide a robust definition for the boundary between liquidlike and gaslike regions, even in those systems without a liquid-gas binodal line. Finally, we discuss these findings in comparison with recent results for Lennard-Jones model fluid and with the notion of the "rigid-nonrigid" fluid separation lines.
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Affiliation(s)
- Taras Bryk
- Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine, 1 Svientsitskii Street, UA-79011 Lviv, Ukraine and Institute of Applied Mathematics and Fundamental Sciences, Lviv Polytechnic National University, 79013 Lviv, Ukraine
| | - Federico Gorelli
- Istituto Nazionale di Ottica INO-CNR, I-50019 Sesto Fiorentino, Italy and European Laboratory for Non Linear Spectroscopy, LENS, I-50019 Sesto Fiorentino, Italy
| | - Giancarlo Ruocco
- Dipartimento di Fisica, Universita di Roma La Sapienza, I-00185, Roma, Italy and Center for Life Nano Science @Sapienza, Istituto Italiano di Tecnologia, 295 Viale Regina Elena, I-00161, Roma, Italy
| | - Mario Santoro
- Istituto Nazionale di Ottica INO-CNR, I-50019 Sesto Fiorentino, Italy and European Laboratory for Non Linear Spectroscopy, LENS, I-50019 Sesto Fiorentino, Italy
| | - Tullio Scopigno
- Dipartimento di Fisica, Universita di Roma La Sapienza, I-00185, Roma, Italy and Center for Life Nano Science @Sapienza, Istituto Italiano di Tecnologia, 295 Viale Regina Elena, I-00161, Roma, Italy
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