Structural Stability and Anharmonic Effect of Metallic Hydrogen FCC Phase Under High Pressures

doi:10.19596/j.cnki.1001-246x.8401

Abstract

Abstract:

First principles molecular dynamics calculation is used to study anharmonic effect of metallic hydrogen system. Lattice vibrations of metallic hydrogen are given, and temperature effect of phonon spectrum of metallic hydrogen is discussed. Phonon dispersions of FCC phases of protium, deuterium and tritium at non-zero temperature were given. Comparing phonon dispersions at different temperatures, we found that 3.6 TPa is the critical pressure of thermodynamic stability at zero temperature, while the critical pressure dropped to 2.8 TPa at a finite temperature (100 K). Anharmonic effect changes significantly stability and phonon dispersions of the system.

Key words: metal hydrogen, anharmonic effect, phonon dispersion, first principles molecular dynamics calculation

Xiaohui WANG, Ping ZHANG. Structural Stability and Anharmonic Effect of Metallic Hydrogen FCC Phase Under High Pressures[J]. Chinese Journal of Computational Physics, 2022, 39(2): 159-164.

Figures/Tables 7

Fig.1 The face-centered cubic crystal structure of metallic hydrogen under TPa

Fig.2 The phonon dispersions of metallic hydrogen under 3, 4 and 6 TPa at 0 K

Fig.3 The phonon dispersions of metallic hydrogen under 3.6 TPa at 0 K

Fig.4 The phonon dispersions of metallic hydrogen (protium) with anharmonic effects at 100 K

Fig.5 The phonon dispersions of metallic hydrogen (protium, deuterium, tritium) at 100 K with the inclusion of anharmonic effects

Fig.6 The phonon dispersions of metallic hydrogen (protium) under 6 TPa at different temperatures with the inclusion of anharmonic effects

Fig.7 (a), (b) two soften phonon modes and (c) phonon density of states of metallic hydrogen under 3.6 TPa at 0 K

References 30

1	WIGNER E , HUNTINGTON H B . On the possibility of a metallic modification of hydrogen[J]. The Journal of Chemical Physics, 1935, 3 (12): 764- 770. DOI
2	ZHANG Q L , LIU H F , LI Q , et al. Path integral Monte Carlo calculations of equation of state of hydrogen[J]. Chinese Journal of Computational Physics, 2019, 36 (4): 379- 385.
3	TANG H X , ZHOU M T , XIN B , et al. Studies on the short-range interaction potential between H₂ molecules[J]. Chinese Journal of Computational Physics, 1993, 10 (1): 117- 119.
4	ZHANG X M , LI Y Y , WAN B N . Calculation of neutral atom density distributions in tokamaks with Monte Carlo method[J]. Chinese Journal of Computational Physics, 1999, 16 (6): 606- 609.
5	MCMAHON J M , MORALES M A , PIERLEONI C , et al. The properties of hydrogen and helium under extreme conditions[J]. Reviews of Modern Physics, 2012, 84 (4): 1607- 1653. DOI
6	MCMINIS J , CLAY R C , LEE D , et al. Molecular to atomic phase transition in hydrogen under high pressure[J]. Physical Review Letters, 2015, 114 (10): 105305(1-6).
7	ASHCROFT N W . Metallic hydrogen: A high-temperature superconductor?[J]. Physical Review Letters, 1968, 21 (26): 1748- 1749. DOI
8	WEIR S T , MITCHELL A C , NELLIS W J . Metallization of fluid molecular hydrogen at 140 GPa (1.4 mbar)[J]. Physical Review Letters, 1996, 76 (11): 1860- 1863. DOI
9	LOUBEYRE P , LETOULLEC R , HAUSERMANN D , et al. X-ray diffraction and equation of state of hydrogen at megabar pressures[J]. Nature, 1996, 383 (6602): 702- 704. DOI
10	BIANCO R , ERREA I , CALANDRA M , et al. High-pressure phase diagram of hydrogen and deuterium sulfides from first principles: Structural and vibrational properties including quantum and anharmonic effects[J]. Physical Review B, 2018, 97 (21): 214101. DOI
11	BORINAGA M , ERREA I , CALANDRA M , et al. Anharmonic effects in atomic hydrogen: Superconductivity and lattice dynamical stability[J]. Physical Review B, 2016, 93 (17): 174308. DOI
12	AZADI S , MONSERRAT B , FOULKES W M C , et al. Dissociation of high-pressure solid molecular hydrogen: A quantum Monte Carlo and anharmonic vibrational study[J]. Physical Review Letters, 2014, 112 (16): 165501(1-5).
13	ROUSSEAU B , BERGARA A . Giant anharmonicity suppresses superconductivity in AlH₃ under pressure[J]. Physical Review B, 2010, 82 (10): 104504. DOI
14	ERREA I , CALANDRA M , MAURI F . First-principles theory of anharmonicity and the inverse isotope effect in superconducting palladium-hydride compounds[J]. Physical Review Letters, 2013, 111 (17): 177002. DOI
15	ERREA I , CALANDRA M , MAURI F . Anharmonic free energies and phonon dispersions from the stochastic selfconsistent harmonic approximation: Application to platinum and palladium hydrides[J]. Physical Review B, 2014, 89 (6): 064302.
16	DROZDOV A P , EREMETS M I , TROYAN I A , et al. Conventional superconductivity at 203 K at high pressures in the sulfur hydride system[J]. Nature, 2015, 525 (7567): 73. DOI
17	ERREA I , CALANDRA M , PICKARD C J , et al. High-pressure hydrogen sulfide from first principles: A strongly anharmonic phonon-mediated superconductor[J]. Physical Review Letters, 2015, 114 (15): 157004. DOI
18	SANO W , KORETSUNE T , TADANO T , et al. Effect of van Hove singularities on high-T_c superconductivity in H₃S[J]. Physical Review B, 2016, 93 (9): 094525. DOI
19	ERREA I , CALANDRA M , PICKARD C J , et al. Quantum hydrogen-bond symmetrization in the superconducting hydrogen sulfide system[J]. Nature, 532, 7597, 81- 84.
20	ZHANG C Y , ZHANG C , CHEN M H , et al. Finite-temperature infrared and Raman spectra of high-pressure hydrogen from first-principles molecular dynamics[J]. Physical Review B, 2018, 98 (14): 144301. DOI
21	LU Y , ZHENG F W , YANG W , et al. Temperature effect on the phase stability of hydrogen C2/c phase from first-principles molecular dynamics calculations[J]. Journal of Physics: Condensed Matter, 2020, 32 (40): 405404. DOI
22	COLE J W , SILVERA I F . Metallic hydrogen propelled launch vehicles for lunar missions[J]. AIP Conference Proceedings, American Institute of Physics, 2009, 1103 (1): 117- 125.
23	ZHANG D B , SUN T , WENTZCOVITCH R M . Phonon quasiparticles and anharmonic free energy in complex systems[J]. Physical Review Letters, 2014, 112 (5): 058501. DOI
24	KOHN W , SHAM L J . Self-consistent equations including exchange and correlation effects[J]. Physical Review, 1965, 140 (4A): A1133. DOI
25	KRESSE G , FURTHMVLLER J . Efficiency of ab-initio total energy calculations for metals and semiconductors using a plane-wave basis set[J]. Computational Materials Science, 1996, 6 (1): 15- 50. DOI
26	KRESSE G , FURTHMVLLER J . Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set[J]. Physical Review B, 1996, 54 (16): 11169. DOI
27	BLÖCHL P E . Projector augmented-wave method[J]. Physical Review B, 1994, 50 (24): 17953- 17979. DOI
28	PERDEW J P , BURKE K , ERNZERHOF M . Generalized gradient approximation made simple[J]. Physical Review Letters, 1996, 77 (18): 3865- 3868. DOI
29	TOGO A , TANAKA I . First principles phonon calculations in materials science[J]. Scripta Materialia, 2015, 108, 1- 5. DOI
30	CARRERAS A , TOGO A , TANAKA I . DynaPhoPy: A code for extracting phonon quasiparticles from molecular dynamics simulations[J]. Computer Physics Communications, 2017, 221, 221- 234. DOI