A5013028857- Advanced Chemical Physics Studies
- Quantum and electron transport phenomena
- Machine Learning in Materials Science
- Catalytic Processes in Materials Science
- Electrocatalysts for Energy Conversion
- Molecular Junctions and Nanostructures
- Catalysis and Oxidation Reactions
- Nanomaterials for catalytic reactions
- 2D Materials and Applications
- Advanced Battery Technologies Research
- Fuel Cells and Related Materials
- Electronic and Structural Properties of Oxides
- Graphene research and applications
- Surface and Thin Film Phenomena
- Magnetic properties of thin films
- Advanced NMR Techniques and Applications
- Chalcogenide Semiconductor Thin Films
- Metal complexes synthesis and properties
- Solid-state spectroscopy and crystallography
- History and advancements in chemistry
- Crystallization and Solubility Studies
- Metal-Organic Frameworks: Synthesis and Applications
- Chemical Thermodynamics and Molecular Structure
- Surface Chemistry and Catalysis
- Advanced Memory and Neural Computing
Trinity College Dublin
2024-2025
Massachusetts Institute of Technology
2017-2022
Indian Institute of Technology Kanpur
2017
Chhatrapati Shahu Ji Maharaj University
2017
We describe how the spin Hall effect (SHE) can be studied from ab initio by combining density functional theory with nonequilibrium Green's functions technique for quantum transport into so-called $\mathrm{DFT}+\mathrm{NEGF}$ method. After laying down our theoretical approach, in particular discussing to compute charge and bond currents, calculations are carried out ideal clean systems. In these, is ballistic linear response limit met. The SHE emerges a central region attached two leads when...
The flat-plane condition is the union of two exact constraints in electronic structure theory: (i) energetic piecewise linearity with fractional electron removal or addition and (ii) invariant energetics change spin a half filled orbital. Semi-local density functional theory (DFT) fails to recover flat plane, exhibiting convex charge errors (FCE) concave (FSE) that are related delocalization static correlation errors. We previously showed DFT+U eliminates FCE but now demonstrate that, like...
Single atom catalysts (SACs) are emergent catalytic materials that have the promise of merging scalability heterogeneous with high activity and economy homogeneous catalysts. Computational, first-principles modeling can provide essential insight into SAC mechanism active site configuration, where sub-nm-scale environment challenge even highest-resolution experimental spectroscopic techniques. Nevertheless, very properties make SACs attractive in catalysis, such as localized d electrons...
<title>Abstract</title> Molecular engineering at metal interfaces has opened new avenues to design functional structures by manipulating charge transfer and hybridization effects.<sup>1–9</sup> While earlier studies have mainly focused on controlling the ferromagnetic order,<sup>10–17</sup> tuning of antiferromagnetic (AF) properties remains largely unexplored. Here, we investigate an enhanced spin Hall effect in Y<sub>3</sub>Fe<sub>5</sub>O<sub>12</sub>(YIG)/PtMn with a C<sub>60</sub>...
We examine the coherent spin-dependent transport properties of van der Waals (vdW) ferromagnet Fe4GeTe2 using density functional theory combined with nonequilibrium Green's function method. Our findings reveal that conductance perpendicular to layers is half-metallic, meaning it almost entirely spin-polarized. This property persists from bulk a single layer, even under significant bias voltages and spin–orbit coupling. Additionally, dynamical mean field for quantum transport, we demonstrate...
Using an evolutionary algorithm, in conjunction with density functional theory (DFT) based electronic, ionic and cell relaxation, we perform extensive search for the crystal structures of possible two dimensional (2D) allotropes phosphorus arsenic.
Density functional theory (DFT) is widely applied to both molecules and materials, but well known energetic delocalization static correlation errors in practical exchange-correlation approximations limit quantitative accuracy. Common methods that correct errors, such as the Hubbard U correction DFT+U or Hartree-Fock exchange global hybrids, do so at cost of worsening errors. We recently introduced an alternate approach [Bajaj et al., J. Chem. Phys. 147, 191101 (2017)] judiciously modified...
Approximate semilocal density functional theory (DFT) is known to underestimate surface formation energies yet paradoxically overbind adsorbates on catalytic transition-metal oxide surfaces due delocalization error. The low-cost DFT + U approach only improves for early oxides or adsorption late oxides. In this work, we demonstrate that inefficacy arises the conventional usage of metal-centered atomic orbitals as projectors within U. We analyze electron rearrangement during and O atom rutile...
While density functional theory (DFT) is widely applied for its combination of cost and accuracy, corrections (e.g., DFT+U) that improve it are often needed to tackle correlated transition-metal chemistry. In principle, the form DFT+U, consisting a set localized atomic orbitals (AOs) quadratic energy penalty deviation from integer occupations those AOs, enables recovery exact conditions piecewise linearity derivative discontinuity. Nevertheless, practical complexes, where both states ligand...
Low-cost, non-empirical corrections to semi-local density functional theory are essential for accurately modeling transition-metal chemistry. Here, we demonstrate the judiciously modified (jmDFT) approach with U and J parameters obtained directly from frontier orbital energetics on a series of complexes. We curate set nine representative Ti(III) V(IV) d1 complexes evaluate their flat-plane errors along fractional spin charge lines. that while jmDFT improves upon both DFT+U DFT standard...
Polymer electrolyte membrane fuel cells (PEMFCs) represent promising energy storage solutions, but challenges remain to maximize their utility. Nafion is frequently employed as the PEMFC material, degradation of can limit life PEMFCs. Using hybrid density functional theory (DFT), we carry out reaction pathway analysis on a range candidate pathways both pristine and defect-containing models Nafion. Degradation initiated by hydrogen radicals involves moderate (ca. 20 kcal/mol) barriers lower...
The predictive accuracy of density functional theory (DFT) is hampered by delocalization errors, especially for correlated systems such as transition-metal complexes. Two complementary strategies have been developed to reduce error: eliminating the global curvature with change in charge, and applying a linear response Hubbard U measure local at metal center fixed charge DFT+U framework. We investigate relationship between two error measures ligand field strength varied number strong-field...
We describe how the spin Hall effect (SHE) can be studied from ab-initio by combining density functional theory with non-equilibrium Green's functions technique for quantum transport into so-called DFT+NEGF method. After laying down our theoretical approach in particular discussing to compute charge and bond currents, calculations are carried out ideal clean systems. In these is ballistic linear response limit met. The SHE emerges a central region attached two leads when we apply bias...
The recent emergence of van der Waals (vdW) ferromagnets has opened new opportunities for designing spintronic devices. We theoretically investigate the coherent spin-dependent transport properties vdW ferromagnet Fe$_4$GeTe$_2$, by using density functional theory combined with non-equilibrium Green's functions method. find that conductance in direction perpendicular to layers is half-metallic, namely it entirely spin-polarized, as a result material's electronic structure. This...
Thermoelectric materials are of great interest for heat energy harvesting applications. One such promising material is TlGaSe$_{2}$, a p-type semiconducting ternary chalcogenide. Recent reports show it can be processed as thin film, opening the door large-scale commercialization. However, TlGaSe$_{2}$ prone to stacking faults along [001] direction and their role in its thermoelectric properties has not been understood date. Herein, investigated via (scanning) transmission electron microscopy...
Polymer electrolyte membrane fuel cells (PEMFCs) represent promising energy storage solutions, but challenges remain to maximize their utility. Nafion is frequently employed as the PEMFC material, degradation of can limit life PEMFCs. Using hybrid density functional theory (DFT), we carry out reaction pathway analysis on a range candidate pathways both pristine and defect-containing models Nafion. Degradation initiated by hydrogen radicals involves moderate (ca. 20 kcal/mol) barriers lower...
Polymer electrolyte membrane fuel cells (PEMFCs) represent promising energy storage solutions, but challenges remain to maximize their utility. Nafion is frequently employed as the PEMFC material, degradation of can limit life PEMFCs. Using hybrid density functional theory (DFT), we carry out reaction pathway analysis on a range candidate pathways both pristine and defect-containing models Nafion. Degradation initiated by hydrogen radicals involves moderate (ca. 20 kcal/mol) barriers lower...
Despite its widespread use, the predictive accuracy of density functional theory (DFT) is hampered by delocalization errors, especially for correlated systems such as transition-metal complexes. Two complementary tuning strategies have been developed to reduce error: eliminating global curvature with respect charge addition or removal, and computing a linear response Hubbard U measure local at metal center fixed applying it complex in DFT+U framework. We investigate relationship between two...
While density functional theory (DFT) is widely applied for its combination of cost and accuracy, corrections (e.g., DFT+U) that improve it are often needed to tackle correlated transition-metal chemistry. In principle, the form DFT+U, consisting a set localized atomic orbitals (AO) quadratic energy penalty deviation from integer occupations those AOs, enables recovery exact conditions piecewise linearity derivative discontinuity. Nevertheless, practical complexes, where both states ligand...
Approximate semi-local density functional theory (DFT) is known to underestimate surface formation energies yet paradoxically overbind adsorbates on catalytic transition-metal oxide surfaces due delocalization error. The low-cost DFT+U approach only improves for early oxides or adsorption late oxides. In this work, we demonstrate that inefficacy arises the conventional usage of metal-centered atomic orbitals as projectors within DFT+U. We analyze electron rearrangement during and O atom...