High pressure and temperature thermoelasticity of hcp osmium from ab initio quasi-harmonic theory
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| Format: | Preprint |
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2025
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| _version_ | 1866915401804283904 |
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| author | Gong, Xuejun Corso, Andrea Dal |
| author_facet | Gong, Xuejun Corso, Andrea Dal |
| contents | We present a systematic ab initio study of the thermoelastic properties of hcp osmium as functions of temperature and pressure within the quasi-harmonic approximation (QHA). The precision of the Zero Static Internal Stress Approximation (ZSISA) and of the volume-constrained ZSISA (V-ZSISA) are rigorously assessed. For osmium, we find negligible deviations between ZSISA and a full free energy minimization (FFEM) approach. Also, the V-ZSISA approximation influences the results very little, as we found already in beryllium, despite the markedly different behavior of the c/a ratio with temperature in the two metals. Our QHA-derived ECs show excellent agreement with available experimental data in the temperature range of 5-301 K, outperforming the results obtained from the quasi-static approximation (QSA). Additionally, we report the pressure-dependent QHA ECs at 5 K, 301 K, and 1000 K, spanning pressures from 0 to 150 kbar. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2507_15354 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | High pressure and temperature thermoelasticity of hcp osmium from ab initio quasi-harmonic theory Gong, Xuejun Corso, Andrea Dal Materials Science We present a systematic ab initio study of the thermoelastic properties of hcp osmium as functions of temperature and pressure within the quasi-harmonic approximation (QHA). The precision of the Zero Static Internal Stress Approximation (ZSISA) and of the volume-constrained ZSISA (V-ZSISA) are rigorously assessed. For osmium, we find negligible deviations between ZSISA and a full free energy minimization (FFEM) approach. Also, the V-ZSISA approximation influences the results very little, as we found already in beryllium, despite the markedly different behavior of the c/a ratio with temperature in the two metals. Our QHA-derived ECs show excellent agreement with available experimental data in the temperature range of 5-301 K, outperforming the results obtained from the quasi-static approximation (QSA). Additionally, we report the pressure-dependent QHA ECs at 5 K, 301 K, and 1000 K, spanning pressures from 0 to 150 kbar. |
| title | High pressure and temperature thermoelasticity of hcp osmium from ab initio quasi-harmonic theory |
| topic | Materials Science |
| url | https://arxiv.org/abs/2507.15354 |