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Das S, Pal AK, Datta A. Pressure Induced Alteration and Stabilization of Intermolecular Stacking in Square-planar Osmium tetracarbonyl. Chemphyschem 2024; 25:e202300720. [PMID: 38087878 DOI: 10.1002/cphc.202300720] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Revised: 12/01/2023] [Indexed: 02/13/2024]
Abstract
Osmium carbonyls are well known to form stable 18-electron complexes like Os(CO)5 , Os2 (CO)9 and Os3 (CO)12 having both bridging and terminal carbonyls. For osmium tetra-carbonyl, Os(CO)4 solid-state packing significantly alters the ground-state structure. The gas-phase stable see-saw geometry converts to a square-planar structure in solid state. Highly efficient intermolecular stacking between Os(CO)4 units assists this transformation. Each Os(CO)4 molecule is stacked in a staggered orientation with respect to each other. Pressure induces a [Xe]4f14 5d6 6s2 (S=2)→[Xe]4f14 5d8 (S=0) electronic transition in osmium stabilize a square planar osmium tetra-carbonyl. Under the influence of isotropic pressure, the molecules not only come closer to each other but their relative orientations also get significantly altered. Calculations show that at P=1 GPa and above, the eclipsed orientation for the intermolecular stacking gets preferred over the staggered form. The staggered→eclipsed intermolecular stacking orientation under pressure is shown to be controlled by London dispersion interactions.
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Affiliation(s)
- Shovan Das
- School of Chemical Science, Indian Association for the Cultivation of Science, 2 A and 2B Raja S. C. Mullick Road, Jadavpur 700032, Kolkata, West Bengal, India
| | - Arun K Pal
- School of Chemical Science, Indian Association for the Cultivation of Science, 2 A and 2B Raja S. C. Mullick Road, Jadavpur 700032, Kolkata, West Bengal, India
| | - Ayan Datta
- School of Chemical Science, Indian Association for the Cultivation of Science, 2 A and 2B Raja S. C. Mullick Road, Jadavpur 700032, Kolkata, West Bengal, India
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Ghosh S, Chowdhury J. Predicting band gaps of ABN 3 perovskites: an account from machine learning and first-principle DFT studies. RSC Adv 2024; 14:6385-6397. [PMID: 38380242 PMCID: PMC10877485 DOI: 10.1039/d4ra00402g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2024] [Accepted: 02/14/2024] [Indexed: 02/22/2024] Open
Abstract
The present paper is primarily focused on predicting the band gaps of nitride perovskites from machine learning (ML) models. The ML models have been framed from the feature descriptors and band gap values of 1563 inorganic nitride perovskites having formation energies <-0.026 eV and band gaps ranging from ∼1.0 to 3.1 eV. Four supervised ML models such as multi-layer perceptron (MLP), gradient boosted decision tree (GBDT), support vector regression (SVR) and random forest regression (RFR) have been considered to predict the band gaps of the said systems. The accuracy of each model has been tested from mean absolute error, root-mean-square error and determination coefficient R2 values. The bivariate plots between the predicted and input band gaps of the compounds for both the training and test datasets have also been estimated. Additionally, two ABN3-type nitride perovskites CeBN3 (B = Mo, W) have been selected and their electronic band structures and optoelectronic properties have been studied from density functional theory (DFT) calculations. The band gap values of the said compounds have been estimated from DFT calculations at PBE, HSE06, G0W0@PBE, G0W0@HSE06 level of theories. The present study will be helpful in exploring the ML models in predicting the band gaps of nitride perovskites which in turn may bear potential applications in photovoltaic cells and optical luminescent devices.
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Affiliation(s)
- Swarup Ghosh
- Department of Physics, Jadavpur University 188, Raja S.C. Mallick Road Kolkata 700032 India
| | - Joydeep Chowdhury
- Department of Physics, Jadavpur University 188, Raja S.C. Mallick Road Kolkata 700032 India
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Cammi R, Chen B. Studying and exploring potential energy surfaces of compressed molecules: a fresh theory from the eXtreme Pressure Polarizable Continuum Model. J Chem Phys 2022; 157:114101. [DOI: 10.1063/5.0104269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
We present a new theory for studying and exploring the potential energy surface of compressed molecular systems as described within the XP-PCM framework. The effective potential energy surface is defined by the sum of the electronic energy of the compressed system and the pressure-volume work that is necessary in order to create the compression cavity at the given condition of pressure. We show that the resulting total energy Gt is related to the electronic energy by a Legendre transform, in which the pressure and volume of the compression cavity are the conjugate variables. We present an analytical expression for the evaluation of the gradient of the total energy ∇Gt to be used for the geometry optimization of equilibrium geometries and transition states of compressed molecular systems. We also show that, as a result of the Legendre transform property, the potential energy surface can be studied explicitly as function of the pressure, leading to an explicit connection with the well-known Hammond postulate. As a proof of concept, we present the application of the theory to studying and determining of the optimized geometry of compressed methane and the transition state of electrocyclic ring-closure of hexatriene and of H-transfer between two methyl radicals.
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Affiliation(s)
- Roberto Cammi
- Dipartimento di Scienze Chimica della Vita e della Sostenibilità Ambientale, Università degli Studi di Parma, Italy
| | - Bo Chen
- Donostia international physics center, Spain
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Sessa F, Rahm M. Electronegativity Equilibration. J Phys Chem A 2022; 126:5472-5482. [PMID: 35939052 PMCID: PMC9393861 DOI: 10.1021/acs.jpca.2c03814] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
Controlling the distribution of electrons in materials
is the holy
grail of chemistry and material science. Practical attempts at this
feat are common but are often reliant on simplistic arguments based
on electronegativity. One challenge is knowing when such arguments
work, and which other factors may play a role. Ultimately, electrons
move to equalize chemical potentials. In this work, we outline a theory
in which chemical potentials of atoms and molecules are expressed
in terms of reinterpretations of common chemical concepts and some
physical quantities: electronegativity, chemical hardness, and the
sensitivity of electronic repulsion and core levels with respect to
changes in the electron density. At the zero-temperature limit, an
expression of the Fermi level emerges that helps to connect several
of these quantities to a plethora of material properties, theories
and phenomena predominantly explored in condensed matter physics.
Our theory runs counter to Sanderson’s postulate of electronegativity
equalization and allows a perspective in which electronegativities
of bonded atoms need not be equal. As chemical potentials equalize
in this framework, electronegativities equilibrate.
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Affiliation(s)
- Francesco Sessa
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden
| | - Martin Rahm
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden
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Rahm M. Electronegativity at the Shock Front. PROPELLANTS EXPLOSIVES PYROTECHNICS 2022. [DOI: 10.1002/prep.202100306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Martin Rahm
- Department of Chemistry and Chemical Engineering Chalmers University of Technology Kemigården 4 SE-412 96 Gothenburg Sweden
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Abstract
Iron carbonyls are known to form 18-electron complexes like Fe(CO)5, Fe2(CO)9, and Fe3(CO)12 having terminal or bridged Fe-CO bonding. Based on genetic algorithm-assisted density functional theory (DFT) calculations, it is predicted that at pressures above 2 GPa, iron tetracarbonyl, Fe(CO)4, attains a square-planar geometry with a 16-electron count. Compression overcomes the [Ar]4s23d6 (S = 2) → [Ar]4s03d8 (S = 0) excitation energy to stabilize a closed-shell Fe(CO)4 with a d8-configuration. Strong σ(4CO) → Fe (dx2-y2) bonding along with Fe(dxz, dyz) and Fe(dxy) → π (CO)4* back-bonding assists the formation of square-planar Fe(CO)4 under pressure. Compression progressively flattens and destabilizes the ambient pressure C2v structure of Fe(CO)4, and beyond 2 GPa, it undergoes a sharp C2v → D4h transition with ΔVunit-cell = 2.1% and trans-θ(OC-Fe-CO) = 180°. Realizing a square-planar geometry in a four-coordinated Fe-carbonyl complex shows the rich prospects of the new chemistry under pressure.
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Affiliation(s)
- Pranab Gain
- School of Chemical Sciences, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, West Bengal, India
| | - Shovan Das
- School of Chemical Sciences, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, West Bengal, India
| | - Ayan Datta
- School of Chemical Sciences, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, West Bengal, India
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Lin J, Yang Q, Li X, Zhang X, Li F, Yang G. Pressure-stabilized hexafluorides of first-row transition metals. Phys Chem Chem Phys 2022; 24:1736-1742. [PMID: 34985073 DOI: 10.1039/d1cp04446j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Fluorine chemistry was demonstrated to show the importance of stretching the limits of chemical synthesis, oxidation state, and chemical bonding at ambient conditions. Thus far, the highest fluorine stoichiometry of a neutral first-row transition-metal fluoride is five, in VF5 and CrF5. Pressure can stabilize new stoichiometric compounds that are inaccessible at ambient conditions. Here, we attempted to delineate the fluorination limits of first-row transition metals at a high pressure through first-principles swarm-intelligence structure searching simulations. Besides reproducing the known compounds, our extensive search has resulted in a plethora of unreported compounds: CrF6, MnF6, FeF4, FeF5, FeF6, and CoF4, indicating that the application of pressure achieves not only the fluorination limit (e.g., hexafluoride) but also the long-sought bulky tetrafluorides. Our current results provide a significant step forward towards a comprehensive understanding of the fluorination limit of first-row transition metals.
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Affiliation(s)
- Jianyan Lin
- State Key Laboratory of Metastable Materials Science & Technology and Key Laboratory for Microstructural Material Physics of Hebei Province, School of Science, Yanshan University, Qinhuangdao 066004, China. .,College of Physics, Changchun Normal University, Changchun 130032, China
| | - Qiuping Yang
- State Key Laboratory of Metastable Materials Science & Technology and Key Laboratory for Microstructural Material Physics of Hebei Province, School of Science, Yanshan University, Qinhuangdao 066004, China. .,Centre for Advanced Optoelectronic Functional Materials Research and Key Laboratory for UV Light-Emitting Materials and Technology of Ministry of Education, Northeast Normal University, Changchun 130024, China
| | - Xing Li
- State Key Laboratory of Metastable Materials Science & Technology and Key Laboratory for Microstructural Material Physics of Hebei Province, School of Science, Yanshan University, Qinhuangdao 066004, China.
| | - Xiaohua Zhang
- State Key Laboratory of Metastable Materials Science & Technology and Key Laboratory for Microstructural Material Physics of Hebei Province, School of Science, Yanshan University, Qinhuangdao 066004, China. .,Centre for Advanced Optoelectronic Functional Materials Research and Key Laboratory for UV Light-Emitting Materials and Technology of Ministry of Education, Northeast Normal University, Changchun 130024, China
| | - Fei Li
- State Key Laboratory of Metastable Materials Science & Technology and Key Laboratory for Microstructural Material Physics of Hebei Province, School of Science, Yanshan University, Qinhuangdao 066004, China.
| | - Guochun Yang
- State Key Laboratory of Metastable Materials Science & Technology and Key Laboratory for Microstructural Material Physics of Hebei Province, School of Science, Yanshan University, Qinhuangdao 066004, China. .,Centre for Advanced Optoelectronic Functional Materials Research and Key Laboratory for UV Light-Emitting Materials and Technology of Ministry of Education, Northeast Normal University, Changchun 130024, China
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Racioppi S, Rahm M. In-Situ Electronegativity and the Bridging of Chemical Bonding Concepts. Chemistry 2021; 27:18156-18167. [PMID: 34668618 PMCID: PMC9299076 DOI: 10.1002/chem.202103477] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Indexed: 12/30/2022]
Abstract
One challenge in chemistry is the plethora of often disparate models for rationalizing the electronic structure of molecules. Chemical concepts abound, but their connections are often frail. This work describes a quantum‐mechanical framework that enables a combination of ideas from three approaches common for the analysis of chemical bonds: energy decomposition analysis (EDA), quantum chemical topology, and molecular orbital (MO) theory. The glue to our theory is the electron energy density, interpretable as one part electrons and one part electronegativity. We present a three‐dimensional analysis of the electron energy density and use it to redefine what constitutes an atom in a molecule. Definitions of atomic partial charge and electronegativity follow in a way that connects these concepts to the total energy of a molecule. The formation of polar bonds is predicted to cause inversion of electronegativity, and a new perspective of bonding in diborane and guanine−cytosine base‐pairing is presented. The electronegativity of atoms inside molecules is shown to be predictive of pKa.
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Affiliation(s)
- Stefano Racioppi
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Kemigården 4, 41258, Gothenburg, Sweden
| | - Martin Rahm
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Kemigården 4, 41258, Gothenburg, Sweden
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From Electronegativity towards Reactivity-Searching for a Measure of Atomic Reactivity. Molecules 2021; 26:molecules26123680. [PMID: 34208693 PMCID: PMC8234329 DOI: 10.3390/molecules26123680] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Revised: 06/09/2021] [Accepted: 06/10/2021] [Indexed: 11/16/2022] Open
Abstract
Pauling introduced the concept of electronegativity of an atom which has played an important role in understanding the polarity and ionic character of bonds between atoms. We set out to define a related concept of atomic reactivity in such a way that it can be quantified and used to predict the stability of covalent bonds in molecules. Guided by the early definition of electronegativity by Mulliken in terms of first ionization energies and Pauling in terms of bond energies, we propose corresponding definitions of atomic reactivity. The main goal of clearly distinguishing the inert gas atoms as nonreactive is fulfilled by three different proposed measures of atomic reactivity. The measure likely to be found most useful is based on the bond energies in atomic hydrides, which are related to atomic reactivities by a geometric average. The origin of the atomic reactivity is found in the symmetry of the atomic environment and related conservation laws which are also the origin of the shell structure of atoms and the periodic table. The reactive atoms are characterized by degenerate or nearly degenerate (several states of the same or nearly the same energy) ground states, while the inert atoms have nondegenerate ground states and no near-degeneracies. We show how to extend the use of the Aufbau model of atomic structure to qualitatively describe atomic reactivity in terms of ground state degeneracy. The symmetry and related conservation laws of atomic electron structures produce a strain (energy increase) in the structure, which we estimate by use of the Thomas-Fermi form of DFT implemented approximately with and without the symmetry and conservation constraints. This simplified and approximate analysis indicates that the total strain energy of an atom correlates strongly with the corresponding atomic reactivity measures but antibonding mechanisms prevent full conversion of strain relaxation to bonding.
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Tandon H, Labarca M, Chakraborty T. A Scale of Atomic Electronegativity Based on Floating Spherical Gaussian Orbital Approach. ChemistrySelect 2021. [DOI: 10.1002/slct.202101142] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Hiteshi Tandon
- Department of Chemistry Manipal University Jaipur Jaipur 303 007 India
| | - Martín Labarca
- Facultad de Filosofia y Letras Instituto de Filosofia “Doctor Alejandro Korn” CONICET - Universidad de Buenos Aires Puán 481, 4to Piso, Oficina 431 1406 - Ciudad Autónoma de Buenos Aires Argentina
| | - Tanmoy Chakraborty
- Department of Chemistry and Biochemistry School of Basic Sciences and Research Sharda University Greater Noida 201 310 India
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