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Possible high-temperature superconductivity in LiCuH at ambient pressure
(2026-12-01)
Tsuppayakorn-aek, Prutthipong
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Thasitha, Sirinee
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Udomkijmongkol, Anan
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Sukmas, Wiwittawin
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Hussain, Tanveer
We theoretically investigate the structural stability, electronic property, and superconductivity of the hydrogen-rich compound LiCuH in its face-centered cubic phase. First-principles calculations show that LiCuH is thermodynamically metastable at ambient pressure but dynamically stable. Moreover, ab initio molecular dynamics (AIMD) simulation at 300 K further confirms that LiCuH remains structurally intact without decomposition. These results suggest that the material may be synthesized under high pressure and retained after decompression. Although thermodynamically metastable at ambient conditions, its dynamic stability supports its persistence after pressure release. Moreover, LiCuH exhibits metallic behavior with a flat band and van Hove singularity (vHS) near the Fermi level and Fermi-surface states dominated by Cu–d and H–s orbitals. Phonon calculations further indicate that hydrogen vibrations dominate the phonon contribution, while the electronic states near the Fermi level govern the coupling strength, resulting in a large electron–phonon coupling constant. Insights into the superconducting temperature () are obtained using various theoretical approaches, which estimate to be in the range of 93–152 K. Bonding analysis further indicates mixed covalent–ionic character within Cu–H octahedra. These results highlight LiCuH as a promising hydrogen-based metastable superconductor for future experimental exploration.
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Structural stabilities, elastic property, and robust topological phases in Janus MoWCO2MXene from first-principles investigation
(2026-02-25)
Thasitha, Sirinee
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Tsuppayakorn-aek, Prutthipong
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Kaewmaraya, Thanayut
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Hussain, Tanveer
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Bovornratanaraks, Thiti
Two-dimensional (2D) topological materials have attracted considerable interest because of their potential applications in next-generation quantum and spintronic devices. In this work, we systematically investigate the structural, mechanical, and electronic properties of Janus MoWCO<inf>2</inf> MXene using first-principles density functional theory (DFT) calculations, both with and without spin–orbit coupling (SOC). The energetically favored O-terminated configurations are examined in detail, revealing that the 2H phase exhibits higher thermodynamic, mechanical, and dynamical stability than the 1T phase. In the absence of SOC, both phases display metallic behavior. Upon inclusion of SOC, a band inversion emerges at the Γ point. In particular, SOC opens a narrow band gap of approximately 0.10 eV in the 2H phase, whereas the 1T phase remains gapless and exhibits semimetallic characteristics. Topological analysis based on helical edge states and Z<inf>2</inf> invariants indicates that 2H-MoWCO<inf>2</inf> is a strong topological insulator candidate, while 1T-MoWCO<inf>2</inf> can be classified as a topological semimetal candidate. These findings suggest that Janus MoWCO<inf>2</inf> MXene represents a promising two-dimensional platform for exploring SOC-driven topological phases and related quantum phenomena.
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Exploring phonon mediated superconductivity of and under high pressure insight from first-principles calculations
(2025-12-01)
Tsuppayakorn-aek, Prutthipong
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Bovornratanaraks, Thiti
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Kotmool, Komsilp
Investigating novel materials under high pressure presents a challenge in condensed matter physics. In this study, we examine and, materials identified through an evolutionary algorithm, which exhibit thermodynamic stability up to at least 100 GPa. Our findings reveal that exhibits a rhombohedral structure () at pressures ranging from 0 GPa to 25 GPa, transitioning to a hexagonal structure () between 50 GPa and 100 GPa. In contrast, is predicted to have a monoclinic structure (C2/m) at low pressures and a hexagonal structure () at higher pressures. Notably, both materials are dynamically stable within the harmonic approximation at pressures beyond 15 GPa for and beyond 25 GPa for. Furthermore, accurately capturing the thermal lattice vibrations of these materials under strong quantum anharmonicity requires advanced methods. Using a stochastic approach to self-consistent harmonic approximation (SSCHA), we introduce anharmonic corrections to further explore lattice dynamics. For superconducting properties, shows a remarkable critical temperature () of 44.5 K at a pressure of 25 GPa, as predicted within the harmonic approximation. In comparison, achieves a of approximately 13 K at a pressure of 50 GPa when anharmonic corrections are applied using the Allen-Dynes modified McMillan equation. Our findings bridge a gap in understanding electronic band structure, phonon linewidth impacts, and vibrational modes under pressure, offering key insights into phase stability and superconducting mechanisms. These findings introduce a promising new class of materials, emphasizing their potential to enrich superconductivity research by advancing previously overlooked substances.
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Strong electron–phonon coupling and predicted high superconducting transition temperature of MXenes revealed in 2H-Mo2N under biaxial stress
(2024-12-15)
Kotmool, Komsilp
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Tsuppayakorn-aek, Prutthipong
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Bovornratanaraks, Thiti
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Kaewmaraya, Thanayut
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Sakdanuphab, Rachsak
Extensive investigations have been conducted on Mo-based MXenes due to their high superconducting temperatures (T<inf>c</inf>). This work theoretically reports strong electron–phonon coupling (EPC) and high T<inf>c</inf> (≈38 K) of 2H-Mo<inf>2</inf>N under biaxial stress, with excellent mechanical properties. EPC and T<inf>c</inf> are elucidated upon dynamically stable strain range. At 0% strain, EPC constant (λ) and T<inf>c</inf> are 1.32 and 22.7 K, respectively. They are improved when subjected to biaxial stresses. Strong EPC with λ over 2.0 occurs at −4%, −2.5%, and 5% strains, yielding enhanced T<inf>c</inf>. The finding suggests that the energy levels of electronic bands at the Fermi level are enhanced by strain, which enhances EPC. Moreover, the impact of functional groups on superconductivity has been investigated. The λ’s of Mo<inf>2</inf>NH<inf>2</inf> and Mo<inf>2</inf>NO<inf>2</inf> are reduced, and T<inf>c</inf> drops nearly to 20.0 and 0.9 K, respectively. This work provides an example of designing 2D superconductors by tuning atomic recipes and strain-dependent engineering.
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Hydrogenation-induced superconducting properties of MgB2 investigated using Migdal–Eliashberg formalism: Insights from a first-principles study
(2024-09-01)
Tsuppayakorn-aek, Prutthipong
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Sukmas, Wiwittawin
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Pluengphon, Prayoonsak
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Petchsirivej, Sukanya
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Sakulkalavek, Aparporn
Theoretical investigation of hydrogenation processes has applied to magnesium diborides under ambient conditions, which identified two structurally stable phases, i.e, Mg<inf>4</inf>B<inf>6</inf>H<inf>2</inf> and Mg<inf>4</inf>B<inf>4</inf>H<inf>4</inf>. These identifications were evaluated through assessments of their lattice dynamics stability using density functional perturbation theory. Both phases exhibit metallic behavior within their electronic band structures. Our findings showcase the significant impact of anisotropic Migdal–Eliashberg calculations, enhancing the superconducting properties within this system and resulting in a notably higher T<inf>c</inf> of 34 K. Mg<inf>4</inf>B<inf>4</inf>H<inf>4</inf> exhibits superconductivity with a T<inf>c</inf> of 17 K under atmospheric conditions, as determined by anisotropic Migdal–Eliashberg calculations. Our study underscores the wide range of structural variations achievable through the hydrogenation of MgB<inf>2</inf> and highlights the crucial importance of hydrogen atom placement within these structures. In addition, the calculation result indicates the influence of band dispersion characteristics on Fermi velocity, a factor attributed to both anharmonicity and harmonicity, which plays a pivotal role in determining the superconducting properties of these materials.
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Thermodynamic and dynamic stability of NaLiC4: Exploring superconductivity in a layered hexagonal compound through first-principles calculations
(2024-06-01)
Pluengphon, Prayoonsak
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Sukmas, Wiwittawin
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Tsuppayakorn-aek, Prutthipong
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Kotmool, Komsilp
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Sakulkalavek, Aparporn
The layered hexagonal compound NaLiC<inf>4</inf> has been thoroughly investigated to assess its thermodynamic and dynamic stability in comparison to its parent compounds NaC<inf>2</inf> and LiC<inf>2</inf>. Utilizing first-principles calculations and phonon analyzes, NaLiC<inf>4</inf> has demonstrated remarkable stability within a pressure range of 10 to 100 GPa, surpassing the thermodynamic stability of NaC<inf>2</inf> and LiC<inf>2</inf>. It exhibits metallic behavior with distinctive electronic bands along high symmetry paths, suggesting a conducive environment for superconductivity. The superconducting transition temperature (T<inf>c</inf>) of NaLiC<inf>4</inf> under different pressures was estimated using the Allen–Dynes equation, with a maximum T<inf>c</inf> of 79 K observed at 10 GPa. However, as pressure increases, T<inf>c</inf> gradually decreases, indicating the significant impact of external pressure conditions on the superconducting properties. Notably, the in-plane E<inf>2g</inf> phonon mode originating from the layered hexagonal structure of carbon atoms plays a crucial role in facilitating electron–phonon coupling and influencing the superconducting behavior and T<inf>c</inf> of NaLiC<inf>4</inf>. These findings highlight the thermodynamic and dynamic stability of NaLiC<inf>4</inf> as a promising candidate for exploring superconductivity, offering insights into its electronic properties, pressure-dependent T<inf>c</inf> behavior, and the influence of specific phonon modes. Further theoretical investigations and experimental studies are necessary to fully unlock the potential of NaLiC<inf>4</inf> and its contribution to the development of high-performance superconductors.
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Role of anharmonicity in phonon-mediated superconductivity of quasi- van der Waals layered XP2 (X = As, Sb, Bi) structures: Insight from first-principles calculations
(2023-10-10)
Tsuppayakorn-aek, Prutthipong
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Pluengphon, Prayoonsak
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Sukmas, Wiwittawin
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Sakulkalavek, Aparporn
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Inceesungvorn, Burapat
It is of utmost importance to prioritize the undertaking of investigating superconductivity, as it represents one of the most intriguing and significant phenomena in the field of condensed matter physics. Our research endeavors to shed light on the metallic state of van der Waals layered XP<inf>2</inf> (X = As, Sb, Bi) structures, which is crucial in predicting their superconducting properties. Employing a first-principle evolutionary algorithm, we predicted the structures of phosphides, including AsP<inf>2</inf>, SbP<inf>2</inf>, and BiP<inf>2</inf>, and determined their energetically stable configurations under atmospheric pressure. To investigate the potential for superconductivity in these structures, we conducted a thorough examination of relevant electronic properties. One of the crucial factors we addressed was the role of anharmonic phonon properties in determining the superconducting state in van der Waals layered structures. Our findings suggest that the introduction of anharmonicity can significantly suppress the superconducting abilities of such structures. Hence, the anharmonicity present in AsP<inf>2</inf>, SbP<inf>2</inf>, and BiP<inf>2</inf> could be held accountable for the lower observed superconducting critical temperature in these van der Waals layered structures.
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Role of Lifshitz transition stabilized carbon hexagon structure from biaxial strain: A case of sodium carbide with superconducting condition
(2023-06-15)
Tsuppayakorn-aek, Prutthipong
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Pluengphon, Prayoonsak
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Sukmas, Wiwittawin
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Sukserm, Akkarach
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Kotmool, Komsilp
We theoretically report on an investigation of sodium carbide system by means of first-principles calculations based on density functional theory. Herein, the diverse sodium–carbon structures are predicted by taking carbon-rich compositions of NaC<inf>2</inf> with a carbon hexagon structure as a starting point. Metallic phases of NaC<inf>2</inf> at a pressure of 100 GPa are predicted to be stabilized by biaxial strain, culminating in the strain-induced electronic topological transitions, also known as the Lifshitz transitions. We found that the flat band accommodates localized electrons around the Fermi level, originating from the effect of biaxial strain, which results in low-velocity electrons forming up to at least 20% of Cooper pairs. According to the respective phonon-mediated superconductivity, NaC<inf>2</inf> is dynamically stable not only without the influence of biaxial strain but also with that of the biaxial tensile strain, indicating possible enhancement of the critical temperature superconductor (T<inf>c</inf>). Furthermore, the estimated T<inf>c</inf> reaches 29.5 K, slightly higher than 24.7 K for the case without biaxial strain. These findings suggest that the possibility of superconductivity is promoted by the applied biaxial tensile strain. Our findings pave the way for future investigation of high superconductivity in carbon-based materials and suggest the possibility of metal-carbides being synthesisable and exhibiting quite a high T<inf>c</inf> superconductivity.
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Nature of electronic topological transition and superconductivity in bismuth under high pressure from ab initio random structure searching
(2021-12-01)
Chaimayo, Wanaruk
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Tsuppayakorn-aek, Prutthipong
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Pluengphon, Prayoonsak
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Kotmool, Komsilp
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Pakornchote, Teerachote
We have predicted the hexagonal close-packed (hcp) structure of bismuth (Bi) using ab initio random structure searching (AIRSS) at extreme conditions. The calculation, which included spin–orbit coupling, shows that the hcp structure is thermodynamically and dynamically stable at high pressure. The electronic band structure calculations suggest the downshifting of the flat band through compression due to Lifshitz transitions. The Fermi surface shape of hcp Bi produces the metallicity in this material. The electron localization function reveals a weak bonding of Bi. The solutions of electronic topological transition and a soft-mode of phonon dispersion provide the possibility for prediction and reduction of the superconducting transition temperature.
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Fe-doped effects on phase transition and electronic structure of CeO2 under compressed conditions from ab initio calculations
(2021-10-01)
Sathupun, Karnchana
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Kotmool, Komsilp
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Tsuppayakorn-aek, Prutthipong
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Pluengphon, Prayoonsak
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Majumdar, Arnab
Ab initio study of high-pressure phase transition and electronic structure of Fe-doped CeO<inf>2</inf> with Fe concentrations of 3.125, 6.25, and 12.5 at% has been reported. At a constant-pressure consideration, the lattice constants and the volume of the supercell were decreased with an increasing concentration of Fe. The average bond length of Fe–O is lower than that of Ce–O. As a result, Fe doping induces the reduced volume of the cell, which is in good agreement with previous experiments. At high pressure (~ 30 GPa), it was found that the transition pressure from the fluorite to the cotunnite orthorhombic phase decreases at a higher concentration of Fe, indicating that the formation energy of the compound is induced by Fe-doping. Furthermore, compression leads to interesting electronic properties too. Under higher pressures, the bandgap increases in the cubic structure under compression and then suddenly plummets after the transition to the orthorhombic phase. The 3d states of Fe mainly induced the impurity states in the bandgap. In both the undoped and Fe-doped systems, the bandgap increased in the cubic phase at high pressure, while the gap and p-d hybridization decrease in the orthorhombic phase.

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