EHPRG

Welcome to the official website of the European High Pressure Research Group (EHPRG).

EHPRG is non-profitable academic association established in 1963 which is devoted to science and technology of matter under high pressure. It organizes an annual meeting which brings together hundreds of scientists of various fields, mainly physics, chemistry, Earth and planetary sciences, bio- and food science and technology.

The reasonable size of the group, low conference fees, and a friendly relationship between the attendants have made EHPRG meetings a major event in the European high-pressure community for more than half a century.

Selection of high-pressure related titles from top scientific journals.

Machine learning accelerated random structure searching: Application to yttrium superhydrides
by J.-B. Charraud
The Journal of Chemical Physics, Volume 156, Issue 20, May 2022.
The search for new superhydrides, promising materials for both hydrogen storage and high temperature superconductivity, made great progress, thanks to atomistic simulations and Crystal Structure Prediction (CSP) algorithms. When they are combined with Density Functional Theory (DFT), these methods are highly reliable and often match a great part of the experimental results. However, systems of increasing complexity (number of atoms and chemical species) become rapidly challenging as the number of minima to explore grows exponentially with the number of degrees of freedom in the simulation cell. An efficient sampling strategy preserving a sustainable computational cost then remains to be found. We propose such a strategy based on an active-learning process where machine learning potentials and DFT simulations are jointly used, opening the way to the discovery of complex structures. As a proof of concept, this method is applied to the exploration of tin crystal structures under various pressures. We showed that the α phase, not included in the learning process, is correctly retrieved, despite its singular nature of bonding. Moreover, all the expected phases are correctly predicted under pressure (20 and 100 GPa), suggesting the high transferability of our approach. The method has then been applied to the search of yttrium superhydrides (YHx) crystal structures under pressure. The YH6 structure of space group Im-3m is successfully retrieved. However, the exploration of more complex systems leads to the appearance of a large number of structures. The selection of the relevant ones to be included in the active learning process is performed through the analysis of atomic environments and the clustering algorithm. Finally, a metric involving a distance based on x-ray spectra is introduced, which guides the structural search toward experimentally relevant structures. The global process (active-learning and new selection methods) is finally considered to explore more complex and unknown YHx phases, unreachable by former CSP algorithms. New complex phases are found, demonstrating the ability of our approach to push back the exponential wall of complexity related to CSP.
23 May 2022 at 12:41pm
Nuclear quantum effects on the dynamics and glass behavior of a monatomic liquid with two liquid states
by Ali Eltareb
The Journal of Chemical Physics, Volume 156, Issue 20, May 2022.
We perform path integral molecular dynamics (PIMD) simulations of a monatomic liquid that exhibits a liquid–liquid phase transition and liquid–liquid critical point. PIMD simulations are performed using different values of Planck’s constant h, allowing us to study the behavior of the liquid as nuclear quantum effects (NQE, i.e., atoms delocalization) are introduced, from the classical liquid (h = 0) to increasingly quantum liquids (h > 0). By combining the PIMD simulations with the ring-polymer molecular dynamics method, we also explore the dynamics of the classical and quantum liquids. We find that (i) the glass transition temperature of the low-density liquid (LDL) is anomalous, i.e., [math] decreases upon compression. Instead, (ii) the glass transition temperature of the high-density liquid (HDL) is normal, i.e., [math] increases upon compression. (iii) NQE shift both [math] and [math] toward lower temperatures, but NQE are more pronounced on HDL. We also study the glass behavior of the ring-polymer systems associated with the quantum liquids studied (via the path-integral formulation of statistical mechanics). There are two glass states in all the systems studied, low-density amorphous ice (LDA) and high-density amorphous ice (HDA), which are the glass counterparts of LDL and HDL. In all cases, the pressure-induced LDA–HDA transformation is sharp, reminiscent of a first-order phase transition. In the low-quantum regime, the LDA–HDA transformation is reversible, with identical LDA forms before compression and after decompression. However, in the high-quantum regime, the atoms become more delocalized in the final LDA than in the initial LDA, raising questions on the reversibility of the LDA–HDA transformation.
24 May 2022 at 12:42pm
Comment on “Anharmonicity and Universal Response of Linear Carbon Chain Mechanical Properties under Hydrostatic Pressure”
by Enlai Gao, Ke Zhou, Lei Shi, and Zhiping Xu
Author(s): Enlai Gao, Ke Zhou, Lei Shi, and Zhiping Xu
[Phys. Rev. Lett. 128, 219601] Published Fri May 27, 2022
27 May 2022 at 12:00pm
Erratum: Stronger Interlayer Interactions Contribute to Faster Hot Carrier Cooling of Bilayer Graphene under Pressure [Phys. Rev. Lett. 126, 027402 (2021)]
by Kun Ni, Jinxiang Du, Jin Yang, Shujuan Xu, Xin Cong, Na Shu, Kai Zhang, Aolei Wang, Fei Wang, Liangbing Ge, Jin Zhao, Yan Qu, Kostya S. Novoselov, Pingheng Tan, Fuhai Su, and Yanwu Zhu
Author(s): Kun Ni, Jinxiang Du, Jin Yang, Shujuan Xu, Xin Cong, Na Shu, Kai Zhang, Aolei Wang, Fei Wang, Liangbing Ge, Jin Zhao, Yan Qu, Kostya S. Novoselov, Pingheng Tan, Fuhai Su, and Yanwu Zhu
[Phys. Rev. Lett. 128, 219902] Published Thu May 26, 2022
26 May 2022 at 12:00pm
Mott-Driven BEC-BCS Crossover in a Doped Spin Liquid Candidate $κ\text{−}(\mathrm{BEDT}\text{−}\mathrm{TTF}{)}_{4}{\mathrm{Hg}}_{2.89}{\mathrm{Br}}_{8}$
by Y. Suzuki, K. Wakamatsu, J. Ibuka, H. Oike, T. Fujii, K. Miyagawa, H. Taniguchi, and K. Kanoda
Author(s): Y. Suzuki, K. Wakamatsu, J. Ibuka, H. Oike, T. Fujii, K. Miyagawa, H. Taniguchi, and K. Kanoda


A doped quantum spin-liquid candidate transitions from one regime of superconductor electron pairing to another as pressure increases, thus widening the potential hosts of unconventional superconductivity.


[Phys. Rev. X 12, 011016] Published Tue Jan 25, 2022
25 Jan 2022 at 11:00am
Tetragonal polymorph of ${\mathrm{BaFe}}_{2}{\mathrm{S}}_{2}\mathrm{O}$ as an antiferromagnetic Mott insulator
by Shi-Jie Song, Yi-Qiang Lin, Bai-Zhuo Li, Si-Qi Wu, Qin-Qing Zhu, Zhi Ren, and Guang-Han Cao
Author(s): Shi-Jie Song, Yi-Qiang Lin, Bai-Zhuo Li, Si-Qi Wu, Qin-Qing Zhu, Zhi Ren, and Guang-Han Cao


We report a tetragonal polymorph of ${\mathrm{BaFe}}_{2}{\mathrm{S}}_{2}\mathrm{O}$ synthesized under high pressures. This $β\text{−}{\mathrm{BaFe}}_{2}{\mathrm{S}}_{2}\mathrm{O}$ phase is structurally characterized by two-dimensional ${\mathrm{Fe}}_{2}\mathrm{O}$ square nets that are sandwiched by …


[Phys. Rev. Materials 6, 055002] Published Fri May 13, 2022
13 May 2022 at 12:00pm
Observation of three superconducting transitions in the pressurized CDW-bearing compound ${\mathrm{TaTe}}_{2}$
by Jing Guo, Cheng Huang, Huixia Luo, Huaixin Yang, Linlin Wei, Shu Cai, Yazhou Zhou, Hengcan Zhao, Xiaodong Li, Yanchun Li, Ke Yang, Aiguo Li, Peijie Sun, Jianqi Li, Qi Wu, Robert J. Cava, and Liling Sun
Author(s): Jing Guo, Cheng Huang, Huixia Luo, Huaixin Yang, Linlin Wei, Shu Cai, Yazhou Zhou, Hengcan Zhao, Xiaodong Li, Yanchun Li, Ke Yang, Aiguo Li, Peijie Sun, Jianqi Li, Qi Wu, Robert J. Cava, and Liling Sun


Transition metal dichalcogenides host a wide variety of lattice and electronic structures, as well as corresponding exotic physical properties, especially under certain tuning conditions. Here, we report the observation of pressure-induced three superconducting transitions in ${\mathrm{TaTe}}_{2}$, …


[Phys. Rev. Materials 6, L051801] Published Mon May 09, 2022
9 May 2022 at 12:00pm
Deformation and slip systems of ${\mathrm{CaCl}}_{2}$-type ${\mathrm{MnO}}_{2}$ under high pressure
by Binbin Yue, Matthias Krug, Carmen Sanchez-Valle, Sébastien Merkel, and Fang Hong
Author(s): Binbin Yue, Matthias Krug, Carmen Sanchez-Valle, Sébastien Merkel, and Fang Hong


Many nonmetals and metal dioxides $M{\mathrm{O}}_{2}$, including the dense form of ${\mathrm{SiO}}_{2}$ stishovite, crystalize in a rutile structure at low pressure and transform to a denser ${\mathrm{CaCl}}_{2}$ structure under high pressure. Structures and transformations in $M{\mathrm{O}}_{2}$ di…


[Phys. Rev. Materials 6, 053603] Published Tue May 03, 2022
3 May 2022 at 12:00pm
Nonlinear deformation and elasticity of BCC refractory metals and alloys
by Vishnu Raghuraman, Michael Widom, and Michael C. Gao
Author(s): Vishnu Raghuraman, Michael Widom, and Michael C. Gao


Application of isotropic pressure or uniaxial strain alters the elastic properties of materials; sufficiently large strains can drive structural transformations. Linear elasticity describes stability against infinitesimal strains, while nonlinear elasticity describes the response to finite deformati…


[Phys. Rev. Materials 6, 053601] Published Mon May 02, 2022
2 May 2022 at 12:00pm
Coexistence of pressure-induced superconductivity and topological surface states in elementary substance Sb
by Zhilong Yang and Haijun Zhang
Author(s): Zhilong Yang and Haijun Zhang


Topological superconductors are expected to host non-Abelian Majorana zero mode which is of fundamental importance for topological quantum computing. However, the discovered topological superconductor candidates are still rare. Here, we systematically studied the topological semimetal antimony Sb th…


[Phys. Rev. Materials 6, 054801] Published Mon May 02, 2022
2 May 2022 at 12:00pm
Introducing density variation and pressure in thermodynamically self-consistent continuum phase-change models including phase-field
by M. J. Welland and N. Ofori-Opoku
Author(s): M. J. Welland and N. Ofori-Opoku


We present a thermodynamically self-consistent method to introduce dilation/density variation in continuum-scale phase-change models. Dilation incurs a pressure response via a hyperelastic contribution to the free energy that generalizes the lattice constraint. The dilation is represented entirely b…


[Phys. Rev. Materials 6, 043805] Published Thu Apr 28, 2022
28 Apr 2022 at 12:00pm
Structure and motifs of iron oxides from 1 to 3 TPa
by Feng Zheng, Yang Sun, Renhai Wang, Yimei Fang, Feng Zhang, Bo Da, Shunqing Wu, Cai-Zhuang Wang, Renata M. Wentzcovitch, and Kai-Ming Ho
Author(s): Feng Zheng, Yang Sun, Renhai Wang, Yimei Fang, Feng Zhang, Bo Da, Shunqing Wu, Cai-Zhuang Wang, Renata M. Wentzcovitch, and Kai-Ming Ho


Iron oxides are fundamental components of planet-forming materials. Understanding the Fe-O system's behavior and properties under high pressure can help us identify many new phases and states possible in exoplanetary interiors, especially terrestrial ones. Using the adaptive genetic algorithm, we in…


[Phys. Rev. Materials 6, 043602] Published Mon Apr 25, 2022
25 Apr 2022 at 12:00pm
Enhancing efficiency and scope of first-principles quasiharmonic approximation methods through the calculation of third-order elastic constants
by Adewumi Bakare and Angelo Bongiorno
Author(s): Adewumi Bakare and Angelo Bongiorno


A novel computational strategy is presented to calculate from first principles the coefficient of thermal expansion and the elastic constants of a material over meaningful intervals of temperature and pressure. This strategy combines a novel implementation of the quasiharmonic approximation to calcu…


[Phys. Rev. Materials 6, 043803] Published Fri Apr 15, 2022
15 Apr 2022 at 12:00pm
Comment on “Electromagnetic force on structured metallic surfaces”
by Demeng Feng, Raymond A. Wambold, Yuzhe Xiao, Chenghao Wan, Zhaoning Yu, Victor W. Brar, and Mikhail A. Kats
Author(s): Demeng Feng, Raymond A. Wambold, Yuzhe Xiao, Chenghao Wan, Zhaoning Yu, Victor W. Brar, and Mikhail A. Kats


In [Phys. Rev. B 92, 115416 (2015)], Velzen and Webb proposed that by structuring a metal film suspended in free space with a periodic array of nanoscale slots, the steady-state optical pressure on the film resulting from an incident plane wave can be substantially enhanced compared to the standard …


[Phys. Rev. B 105, 207401] Published Fri May 27, 2022
27 May 2022 at 12:00pm
Electronic and optical properties of crystalline nitrogen versus black phosphorus: A comparative first-principles study
by Alexander N. Rudenko, Swagata Acharya, Ferenc Tasnádi, Dimitar Pashov, Alena V. Ponomareva, Mark van Schilfgaarde, Igor A. Abrikosov, and Mikhail I. Katsnelson
Author(s): Alexander N. Rudenko, Swagata Acharya, Ferenc Tasnádi, Dimitar Pashov, Alena V. Ponomareva, Mark van Schilfgaarde, Igor A. Abrikosov, and Mikhail I. Katsnelson


Crystalline black nitrogen (BN) is an allotrope of nitrogen with the black phosphorus (BP) structure recently synthesized at high pressure by two independent research groups [Ji et al., Sci. Adv. 6, eaba9206 (2020); Laniel et al., Phys. Rev. Lett. 124, 216001 (2020)]. Here, we present a systematic…


[Phys. Rev. B 105, 205135] Published Thu May 26, 2022
26 May 2022 at 12:00pm
Optimal alloying in hydrides: Reaching room-temperature superconductivity in ${\mathrm{LaH}}_{10}$
by Tianchun Wang, José A. Flores-Livas, Takuya Nomoto, Yanming Ma, Takashi Koretsune, and Ryotaro Arita
Author(s): Tianchun Wang, José A. Flores-Livas, Takuya Nomoto, Yanming Ma, Takashi Koretsune, and Ryotaro Arita


Doping represents one of the most promising avenues for optimizing superconductors, such as high-pressure conventional superconductors with record-breaking critical temperatures. In this work, we perform an extensive search for substitutional dopants in ${\mathrm{LaH}}_{10}$, looking for elements th…


[Phys. Rev. B 105, 174516] Published Wed May 25, 2022
25 May 2022 at 12:00pm
Quantum and temperature effects on the crystal structure of superhydride ${\mathrm{LaH}}_{10}$: A path integral molecular dynamics study
by Yuta Watanabe, Takuya Nomoto, and Ryotaro Arita
Author(s): Yuta Watanabe, Takuya Nomoto, and Ryotaro Arita


By classical and path integral molecular dynamics simulations, we study the pressure-temperature ($P\text{−}T$) phase diagram of ${\mathrm{LaH}}_{10}$ to clarify the impact of temperature and atomic zero-point motions. We calculate the XRD pattern and analyze the space group of the crystal structure…


[Phys. Rev. B 105, 174111] Published Tue May 24, 2022
24 May 2022 at 12:00pm
Topological metamagnetism: Thermodynamics and dynamics of the transition in spin ice under uniaxial compression
by L. Pili, A. Steppke, M. E. Barber, F. Jerzembeck, C. W. Hicks, P. C. Guruciaga, D. Prabhakaran, R. Moessner, A. P. Mackenzie, S. A. Grigera, and R. A. Borzi
Author(s): L. Pili, A. Steppke, M. E. Barber, F. Jerzembeck, C. W. Hicks, P. C. Guruciaga, D. Prabhakaran, R. Moessner, A. P. Mackenzie, S. A. Grigera, and R. A. Borzi


Metamagnetic transitions are analogs of a pressure-driven gas-liquid transition in water. In insulators, they are marked by a superlinear increase in the magnetization that occurs at a field strength set by the spin exchange interactions. Here we study topological metamagnets, in which the magnetiza…


[Phys. Rev. B 105, 184422] Published Tue May 24, 2022
24 May 2022 at 12:00pm
Dimensionality switching and superconductivity transition in dense $1T\text{−}{\mathrm{HfSe}}_{2}$
by Can Tian, Yiping Gao, Fubo Tian, Xin Wang, Zihan Zhang, Defang Duan, Xiaoli Huang, and Tian Cui
Author(s): Can Tian, Yiping Gao, Fubo Tian, Xin Wang, Zihan Zhang, Defang Duan, Xiaoli Huang, and Tian Cui


The quest for new transition metal dichalcogenides (TMDs) with outstanding electronic properties is a particularly significant and interesting subject. The use of nonconventional methods of materials synthesis, especially pressure engineering, shows great potential for breakthrough discoveries in TM…


[Phys. Rev. B 105, L180506] Published Tue May 24, 2022
24 May 2022 at 12:00pm
Pressure-induced electronic transitions in samarium monochalcogenides
by Debalina Banerjee, Evgeny Plekhanov, Ivan Rungger, and Cedric Weber
Author(s): Debalina Banerjee, Evgeny Plekhanov, Ivan Rungger, and Cedric Weber


The pressure-induced isostructural insulator-to-metal transition for SmS is characterized by the presence of an intermediate valence state at higher pressure which cannot be captured by density functional theory. As a direct outcome of including the charge and spin fluctuations incorporated in dynam…


[Phys. Rev. B 105, 195135] Published Mon May 23, 2022
23 May 2022 at 12:00pm
Elastic properties of body-centered cubic iron in Earth's inner core
by Anatoly B. Belonoshko, Sergei I. Simak, Weine Olovsson, and Olga Yu. Vekilova
Author(s): Anatoly B. Belonoshko, Sergei I. Simak, Weine Olovsson, and Olga Yu. Vekilova


The solid Earth's inner core (IC) is a sphere with a radius of about 1300 km in the center of the Earth. The information about the IC comes mainly from seismic studies. The composition of the IC is obtained by matching the seismic data and properties of candidate phases subjected to high pressure (P…


[Phys. Rev. B 105, L180102] Published Mon May 23, 2022
23 May 2022 at 12:00pm
High pressure effect in the near-infrared emission of Nd3+-doped alkali silicate glasses
by Israel Montoya Matos
Volume 42, Issue 1, March 2022, Page 1-13
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16 Dec 2021 at 1:56pm
Exploration of the best reference material on anelastic measurement by cyclic loading under high pressure
by Chao Liu
Volume 42, Issue 1, March 2022, Page 14-28
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13 Dec 2021 at 9:33am
Three-wall piston-cylinder type pressure cell for muon-spin rotation/relaxation experiments
by Rustem Khasanov
Volume 42, Issue 1, March 2022, Page 29-46
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16 Dec 2021 at 1:59pm
High pressure structural phase transitions in Dysprosium to 202 GPa
by Kevin M. Hope
Volume 42, Issue 1, March 2022, Page 47-56
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17 Jan 2022 at 10:21am
High pressure photoluminescence of bismuth-doped yttria-alumina-silica glass
by Mark A. Hughes
Volume 42, Issue 1, March 2022, Page 94-104
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28 Feb 2022 at 5:33am
Effect of high hydrostatic pressure treatment with room-temperature ionic liquid 1-ethyl-3-methylimidazolium acetate - dimethyl sulfoxide mixture on lipid extraction from Chlorella vulgaris
by Yuki Kojima
Volume 42, Issue 1, March 2022, Page 105-120
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11 Mar 2022 at 3:08am
Improvement of nano-polycrystalline diamond anvil cells with Zr-based bulk metallic glass cylinder for higher pressures: application to Laue-TOF diffractometer
by Keishiro Yamashita
Volume 42, Issue 1, March 2022, Page 121-135
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11 Mar 2022 at 3:08am
Review: inactivation of very heat-resistant spores of Bacilus sporothermodurans by high pressure treatment combined with others treatments
by Chedia Aouadhi
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27 May 2022 at 9:09am
Progress and prospects for cuprate high temperature superconductors under pressure
by Alexander C. Mark
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19 Apr 2022 at 1:55pm
High pressure neutron diffraction on WAND2 with a Paris-Edinburgh press
by M-E. Donnelly
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19 Apr 2022 at 1:41pm

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