Article
Multidisciplinary Sciences
Elliot Snider, Nathan Dasenbrock-Gammon, Raymond McBride, Mathew Debessai, Hiranya Vindana, Kevin Vencatasamy, Keith Lawler, Ashkan Salamat, Ranga P. Dias
Article
Chemistry, Inorganic & Nuclear
Keith Lawler, Dean Smith, Shaun R. Evans, Antonio M. dos Santos, Jamie J. Molaison, Jan-Willem G. Bos, Hannu Mutka, Paul F. Henry, Dimitri N. Argyriou, Ashkan Salamat, Simon A. J. Kimber
Summary: The study of CuMnO2 reveals that high pressure decouples different degrees of freedom, leading to an isostuctural phase transition at around 10 GPa with a reversible collapse of the c-axis. High pressure selectively activates the dynamical instabilities of Cu+ cations, with a predicted reemergence of magnetism at the highest pressures.
INORGANIC CHEMISTRY
(2021)
Article
Physics, Multidisciplinary
Elliot Snider, Nathan Dasenbrock-Gammon, Raymond McBride, Xiaoyu Wang, Noah Meyers, Keith V. Lawler, Eva Zurek, Ashkan Salamat, Ranga P. Dias
Summary: The recent observation of room-temperature superconductivity is expected to drive the discovery of new, dense, hydrogen-rich materials, including rare earth metal superhydrides. A study reported the synthesis of a yttrium superhydride that exhibits superconductivity at a critical temperature of 262 K at 182 ± 8 GPa, with the assistance of a palladium thin film. It was found that the phonon-mediated superconductivity is established by the observation of zero resistance, an isotope effect, and the reduction of T-c under an external magnetic field, with the upper critical magnetic field at 103 T at zero temperature.
PHYSICAL REVIEW LETTERS
(2021)
Article
Chemistry, Multidisciplinary
Konstantin E. German, Alexander M. Fedoseev, Mikhail S. Grigoriev, Gayane A. Kirakosyan, Thomas Dumas, Christophe Den Auwer, Philippe Moisy, Keith V. Lawler, Paul M. Forster, Frederic Poineau
Summary: The compound [H7O3](4)[Tc20O68] · 4H2O[1] was prepared from a concentrated Tc2O7 solution over anhydrous H2SO4. The first polyanionic species for technetium, [Tc20O68](4-), was characterized with its unique structure and electronic transitions. X-ray absorption spectroscopy of red HTcO4 solutions provided additional insights into the compound's behavior in aqueous solution.
CHEMISTRY-A EUROPEAN JOURNAL
(2021)
Article
Chemistry, Physical
Evgeny Epifanovsky, Andrew T. B. Gilbert, Xintian Feng, Joonho Lee, Yuezhi Mao, Narbe Mardirossian, Pavel Pokhilko, Alec F. White, Marc P. Coons, Adrian L. Dempwolff, Zhengting Gan, Diptarka Hait, Paul R. Horn, Leif D. Jacobson, Ilya Kaliman, Jorg Kussmann, Adrian W. Lange, Ka Un Lao, Daniel S. Levine, Jie Liu, Simon C. McKenzie, Adrian F. Morrison, Kaushik D. Nanda, Felix Plasser, Dirk R. Rehn, Marta L. Vidal, Zhi-Qiang You, Ying Zhu, Bushra Alam, Benjamin J. Albrecht, Abdulrahman Aldossary, Ethan Alguire, Josefine H. Andersen, Vishikh Athavale, Dennis Barton, Khadiza Begam, Andrew Behn, Nicole Bellonzi, Yves A. Bernard, Eric J. Berquist, Hugh G. A. Burton, Abel Carreras, Kevin Carter-Fenk, Romit Chakraborty, Alan D. Chien, Kristina D. Closser, Vale Cofer-Shabica, Saswata Dasgupta, Marc de Wergifosse, Jia Deng, Michael Diedenhofen, Hainam Do, Sebastian Ehlert, Po-Tung Fang, Shervin Fatehi, Qingguo Feng, Triet Friedhoff, James Gayvert, Qinghui Ge, Gergely Gidofalvi, Matthew Goldey, Joe Gomes, Cristina E. Gonzalez-Espinoza, Sahil Gulania, Anastasia O. Gunina, Magnus W. D. Hanson-Heine, Phillip H. P. Harbach, Andreas Hauser, Michael F. Herbst, Mario Hernandez Vera, Manuel Hodecker, Zachary C. Holden, Shannon Houck, Xunkun Huang, Kerwin Hui, Bang C. Huynh, Maxim Ivanov, Adam Jasz, Hyunjun Ji, Hanjie Jiang, Benjamin Kaduk, Sven Kaehler, Kirill Khistyaev, Jaehoon Kim, Gergely Kis, Phil Klunzinger, Zsuzsanna Koczor-Benda, Joong Hoon Koh, Dimitri Kosenkov, Laura Koulias, Tim Kowalczyk, Caroline M. Krauter, Karl Kue, Alexander Kunitsa, Thomas Kus, Istvan Ladjanszki, Arie Landau, Keith Lawler, Daniel Lefrancois, Susi Lehtola, Run R. Li, Yi-Pei Li, Jiashu Liang, Marcus Liebenthal, Hung-Hsuan Lin, You-Sheng Lin, Fenglai Liu, Kuan-Yu Liu, Matthias Loipersberger, Arne Luenser, Aaditya Manjanath, Prashant Manohar, Erum Mansoor, Sam F. Manzer, Shan-Ping Mao, Aleksandr Marenich, Thomas Markovich, Stephen Mason, Simon A. Maurer, Peter F. McLaughlin, Maximilian F. S. J. Menger, Jan-Michael Mewes, Stefanie A. Mewes, Pierpaolo Morgante, J. Wayne Mullinax, Katherine J. Oosterbaan, Garrette Paran, Alexander C. Paul, Suranjan K. Paul, Fabijan Pavosevic, Zheng Pei, Stefan Prager, Emil Proynov, Adam Rak, Eloy Ramos-Cordoba, Bhaskar Rana, Alan E. Rask, Adam Rettig, Ryan M. Richard, Fazle Rob, Elliot Rossomme, Tarek Scheele, Maximilian Scheurer, Matthias Schneider, Nickolai Sergueev, Shaama M. Sharada, Wojciech Skomorowski, David W. Small, Christopher J. Stein, Yu-Chuan Su, Eric J. Sundstrom, Zhen Tao, Jonathan Thirman, Gabor J. Tornai, Takashi Tsuchimochi, Norm M. Tubman, Srimukh Prasad Veccham, Oleg Vydrov, Jan Wenzel, Jon Witte, Atsushi Yamada, Kun Yao, Sina Yeganeh, Shane R. Yost, Alexander Zech, Igor Ying Zhang, Xing Zhang, Yu Zhang, Dmitry Zuev, Alan Aspuru-Guzik, Alexis T. Bell, Nicholas A. Besley, Ksenia B. Bravaya, Bernard R. Brooks, David Casanova, Jeng-Da Chai, Sonia Coriani, Christopher J. Cramer, Gyorgy Cserey, A. Eugene DePrince, Robert A. DiStasio, Andreas Dreuw, Barry D. Dunietz, Thomas R. Furlani, William A. Goddard, Sharon Hammes-Schiffer, Teresa Head-Gordon, Warren J. Hehre, Chao-Ping Hsu, Thomas-C Jagau, Yousung Jung, Andreas Klamt, Jing Kong, Daniel S. Lambrecht, WanZhen Liang, Nicholas J. Mayhall, C. William McCurdy, Jeffrey B. Neaton, Christian Ochsenfeld, John A. Parkhill, Roberto Peverati, Vitaly A. Rassolov, Yihan Shao, Lyudmila Slipchenko, Tim Stauch, Ryan P. Steele, Joseph E. Subotnik, Alex J. W. Thom, Alexandre Tkatchenko, Donald G. Truhlar, Troy Van Voorhis, Tomasz A. Wesolowski, K. Birgitta Whaley, H. Lee Woodcock, Paul M. Zimmerman, Shirin Faraji, Peter M. W. Gill, Martin Head-Gordon, John M. Herbert, Anna Krylov
Summary: This article summarizes the technical advances in the fifth major release of the Q-Chem quantum chemistry program package, which includes developments since 2015. Q-Chem 5 features a variety of new many-body methods, core-level spectroscopy modeling tools, vibronic spectrum calculation methods, high-performance capabilities, and support for multithreaded parallelism. The software is continuously evolving with the support of an open teamware model and increasingly modular design, backed by a community of over 100 active academic developers.
JOURNAL OF CHEMICAL PHYSICS
(2021)
Article
Physics, Multidisciplinary
Dylan Durkee, Nathan Dasenbrock-Gammon, G. Alexander Smith, Elliot Snider, Dean Smith, Christian Childs, Simon A. J. Kimber, Keith Lawler, Ranga P. Dias, Ashkan Salamat
Summary: A reversible density-driven insulator-to-metal transition in high-spin MnS2 was observed experimentally, with a significant drop in electrical resistance at 12 GPa. Density functional theory simulations revealed the unexpected metallization mechanism involving previously unoccupied antibonding states. Furthermore, the emergence of low-spin insulating arsenopyrite and the return to an insulating electronic state were confirmed at 36 GPa.
PHYSICAL REVIEW LETTERS
(2021)
Article
Materials Science, Multidisciplinary
Emily Siska, Dean Smith, Christian Childs, Daniel Koury, Paul M. Forster, Keith Lawler, Ashkan Salamat
Summary: In this study, we report the synthesis and structure of the second allotrope of technetium, beta-Tc. Transformative pathways were accessed under extreme conditions, and in situ synchrotron x-ray diffraction and Raman spectroscopy were used to confirm the findings. The beta-Tc exhibits a tetragonal structure with further distortion under pressure, and unexpected volume lowering when doped with nitrogen, potentially indicating a rare electronic phase transition in a 4d element.
PHYSICAL REVIEW MATERIALS
(2021)
Retraction
Multidisciplinary Sciences
Elliot Snider, Nathan Dasenbrock-Gammon, Raymond McBride, Mathew Debessai, Hiranya Vindana, Kevin Vencatasamy, Keith V. Lawler, Ashkan Salamat, Ranga P. Dias
Article
Chemistry, Inorganic & Nuclear
Shuto Asano, Ken Niwa, Keith V. Lawler, Saori Kawaguchi-Imada, Takuya Sasaki, Masashi Hasegawa
Summary: A novel high-pressure phase of manganese mononitride (NiAs-type MnN) was synthesized successfully through a pressure-induced phase transition from a tetragonal distorted NaCl-type MnN at pressures above approximately 55 GPa. This is the first example of a nitride with a reversible structural phase transition from the distorted NaCl-type to the NiAs-type structure. The NiAs-type MnN has higher density and bulk modulus compared to the distorted NaCl-type one.
INORGANIC CHEMISTRY
(2023)
Article
Chemistry, Multidisciplinary
G. Alexander Smith, Ines E. Collings, Elliot Snider, Dean Smith, Sylvain Petitgirard, Jesse S. Smith, Melanie White, Elyse Jones, Paul Ellison, Keith Lawler, Ranga P. Dias, Ashkan Salamat
Summary: We report a previously unobserved superconducting state of the photosynthesized carbonaceous sulfur hydride (C-S-H) system with a maximum T-C of 191(1) K below 100 GPa. X-ray diffraction and simulations reveal that the molecular-like structure of the system remains up to 100 GPa.
CHEMICAL COMMUNICATIONS
(2022)
Article
Chemistry, Multidisciplinary
Dean Sayre, Emily Siska, G. Alexander Smith, Nicholas Chang, Changyong Park, Frederic Poineau, Craig P. Schwartz, Keith V. Lawler, Ashkan Salamat
Summary: This study reveals that TcS2 undergoes a charge transfer transition above 28 GPa, resulting in the formation of a new arsenopyrite phase. Surprisingly, this new phase resembles Mn-dichalcogenides rather than the expected Re-dichalcogenides and involves the formation of S-S and Tc-Tc bonds.
CHEMICAL COMMUNICATIONS
(2022)
Article
Materials Science, Multidisciplinary
Lazar Novakovic, Dean Sayre, Daniel Schacher, Ranga P. Dias, Ashkan Salamat, Keith Lawler
Summary: Recent developments in high temperature superconducting materials have highlighted the importance of numerical evaluation of the superconducting transition temperature (Tc) as a means of identification. Existing methods often do not agree with each other or experiment, possibly due to the neglect of dispersion interactions. This study evaluates the effect of dispersion interactions on the predicted superconducting properties of covalent superhydride materials and finds that dispersion has a sizable effect on increasing the electron-phonon coupling.
Article
Materials Science, Multidisciplinary
G. Alexander Smith, Daniel Schacher, Jasmine K. Hinton, Daniel Sneed, Changyong Park, Sylvain Petitgirard, Keith Lawler, Ashkan Salamat
Summary: The study confirms the anomalous behavior of GeO2 during the rutile to CaCl2 phase transition, with density functional theory calculations showing a decrease in enthalpic barrier to oxygen displacements with increasing pressure, leading to the formation of small polarons in the distorted state band structure.
Article
Chemistry, Multidisciplinary
Emily Siska, Dean Smith, Ashkan Salamat, Keith V. Lawler, Barbara Lavina, Frederic Poineau, Paul M. Forster
Summary: The synthesis and phase stability of TcN, Tc2N, and a substoichiometric TcNx were demonstrated under high pressure and temperature conditions, with a previously unpredicted structure identified for TcN through crystal structure prediction.
CHEMICAL COMMUNICATIONS
(2021)
Article
Chemistry, Multidisciplinary
James Louis-Jean, Samundeeswari M. Balasekaran, Keith Lawler, Adrian Sanchis-Perucho, Jose Martinez-Lillo, Dean Smith, Paul M. Forster, Ashkan Salamat, Frederic Poineau
Summary: The (NH4)(2)[ReF6] (1) salt was thoroughly studied using X-ray diffraction, Raman spectroscopy, theoretical calculations, and magnetic measurements, revealing unique Raman spectrum characteristics and magnetic properties at low temperatures. The coexistence of metamagnetism and slow relaxation of magnetization in 1 is unusual in molecular systems based on paramagnetic 5d metal ions reported so far.