Dil Kumar Limbu - Academia.edu (original) (raw)

Papers by Dil Kumar Limbu

arXiv (Cornell University), Dec 4, 2019

Journal of chemical physics online/The Journal of chemical physics/Journal of chemical physics, Apr 1, 2024

Software Impacts, Feb 29, 2024

Journal of Chemical Information and Modeling, Oct 8, 2023

arXiv (Cornell University), Oct 31, 2022

The advent of π-stacked layered metal-organic frameworks (MOFs) opened up new horizons for design... more The advent of π-stacked layered metal-organic frameworks (MOFs) opened up new horizons for designing compact MOF-based devices as they offer unique electrical conductivity on top of permanent porosity and exceptionally high surface area. By taking advantage of the modular nature of these electrically conductive (EC) MOFs, an unlimited number of materials can be created for applications in electronic devices such as battery electrodes, supercapacitors, and spintronics. Permutation of structural building blocks including different metal nodes and organic linkers results in new systems with unprecedented and unexplored physical and chemical properties. With the ultimate goal of providing a platform for accelerated materials design and discovery, here, we lay the foundations towards creation of the first comprehensive database of EC-MOFs with an experimentally guided approach. The first phase of this database, 1

Most of chemistry in nanoporous materials with small pore sizes and windows is known to occur on ... more Most of chemistry in nanoporous materials with small pore sizes and windows is known to occur on the surface which is in immediate contact with substrate/solvent, rather than inside pores and channels. Here, we report the results of our comprehensive atomistic molecular dynamics simulations on deciphering the intermolecular hydrogen bond network of water on outer surface of a nanoparticle model of ZIF-8 vs. inner surfaces of its pristine crystalline bulk model. Using a finite ~5.1 nm nanoparticle model with edges containing under--coordinated Zn2+ metal sites we show that water exposed to the surface of the nanoparticle exhibits both interfacial and bulk-like characters. Furthermore, we illustrate that as water content increases larger droplets are formed with water molecules starting to diffuse into the nanopores. While the confined water in the crystalline bulk simulations is pushed to the vacant pores due to hydrophobic inner surfaces, the outer surface water molecules form chemi...

Chemistry of Materials, 2020

Bulletin of the American Physical Society, 2017

physica status solidi (b), 2021

This article presents an ab initio study of hydrogen dynamics inside nanometer‐size voids in amor... more This article presents an ab initio study of hydrogen dynamics inside nanometer‐size voids in amorphous silicon (a‐Si) within the framework of the density‐functional theory for a varying hydrogen load of 10–30 atoms per void at the low and high temperature of 400 and 700 K, respectively. Using the local density approximation (LDA) and its generalized‐gradient counterpart (GGA), the dynamics of hydrogen atoms inside the voids are examined with an emphasis on the diffusion of H atoms/molecules, and the resulting nanostructural changes of the void surfaces. The results from simulations suggest that the microstructure of the hydrogen distribution on the void surfaces and the morphology of the voids are characterized by the presence of a significant number of monohydride SiH bonds, along with a few dihydride configurations. The study also reveals that a considerable number (about 10–45 at%) of total H atoms inside a void can appear as H2 molecules for a hydrogen load of 10–30 H atoms per...

Scientific Reports, 2020

X-ray diffraction, Amorphous silicon, Multi-objective optimization, Monte Carlo methods. This pap... more X-ray diffraction, Amorphous silicon, Multi-objective optimization, Monte Carlo methods. This paper addresses a difficult inverse problem that involves the reconstruction of a three-dimensional model of tetrahedral amorphous semiconductors via inversion of diffraction data. By posing the material-structure determination as a multiobjective optimization program, it has been shown that the problem can be solved accurately using a few structural constraints, but no total-energy functionals/forces, which describe the local chemistry of amorphous networks. The approach yields highly realistic models of amorphous silicon, with no or only a few coordination defects (≤1%), a narrow bond-angle distribution of width 9–11.5°, and an electronic gap of 0.8–1.4 eV. These data-driven information-based models have been found to produce electronic and vibrational properties of a-Si that match accurately with experimental data and rival that of the Wooten-Winer-Weaire models. The study confirms the e...

Journal of Physics: Conference Series, 2017

We present a force-biased Monte Carlo (FMC) method for structural modeling of transition metal cl... more We present a force-biased Monte Carlo (FMC) method for structural modeling of transition metal clusters of Fe, Ni, and Cu with 5 to 60 atoms. By employing the Finnis-Sinclair potential for Fe and the Sutton-Chen potential for Ni and Cu, the total energy of the clusters is minimized using a method that utilizes atomic forces in Monte Carlo simulations. The structural configurations of the clusters obtained from this biased Monte Carlo approach are analyzed and compared with the same from the Cambridge Cluster Database (CCD). The results show that the total-energy of the FMC clusters is very close to the corresponding value of the CCD clusters as listed in the Cambridge Cluster Database. A comparison of the FMC and CCD clusters is presented by computing the pair-correlation function, the bond-angle distribution, and the distribution of atomic-coordination numbers in the first-coordination shell, which provide information about the two-body and three-body correlation functions, the local atomic structure, and the bonding environment of the atoms in the clusters.

Journal of Physics: Conference Series, 2019

The putative ground-state structures of 13-atom Cu and Ag clusters have been studied using ab ini... more The putative ground-state structures of 13-atom Cu and Ag clusters have been studied using ab initio molecular-dynamics (AIMD) based on density-functional theory (DFT). An ensemble of low-energy configurations, collected along the AIMD trajectory and optimized to nearest local minimum-energy configurations, were studied. An analysis of the results suggests the existence of low-symmetric bilayer structures as strong candidates for the putative ground-state structure of Cu13 and Ag13 clusters. These bilayer structures are markedly different from a buckled bi-planar (BBP) configuration and energetically favorable, by about 0.4–0.5 eV, than the latter proposed earlier by others. Our study reveals that the structure of the resulting putative global-minimum configuration is essentially independent of the nature of basis functions (i.e., plane waves vs. pseudoatomic orbitals) employed in the calculations, for a given exchange-correlation functional. The structural configurations obtained f...

Physical Review B, 2017

We present a force-biased Monte Carlo (FMC) method for structural modeling of the transition-meta... more We present a force-biased Monte Carlo (FMC) method for structural modeling of the transition-metal clusters of Fe, Ni, and Cu of size 13, 30, and 55 atoms. By employing the Finnis-Sinclair potential for Fe and the Sutton-Chen potential for Ni and Cu, the total energy of the clusters is minimized using the local gradient of the potentials in Monte Carlo simulations. The structural configurations of the clusters, obtained from the biased Monte Carlo approach, are analyzed and compared with the same from the Cambridge Cluster Database (CCD) upon relaxation of the clusters using the first-principles density-functional code NWChem. The results show that the total-energy value and the structure of the FMC clusters are essentially identical to the corresponding value and the structure of the CCD clusters. A comparison of the NWChem-relax FMC and CCD structures is presented by computing the pair-correlation function, the bond-angle distribution, the coordination number of the first-coordination shell, and the Steinhardt bond-orientational order parameter, which provide information about the two-and three-body correlation functions, the local bonding environment of the atoms, and the geometry of the clusters. An atom-by-atom comparison of the FMC and CCD clusters is also provided by superposing one set of clusters onto another, and the electronic properties of the clusters are addressed by computing the density of electronic states.

Physical Review Materials, 2018

Diffraction data play an important role in the structural characterizations of solids. While reve... more Diffraction data play an important role in the structural characterizations of solids. While reverse Monte Carlo (RMC) and similar methods provide an elegant approach to (re)construct a three-dimensional model of non-crystalline solids, a satisfactory solution to the RMC problem is still not available. Following our earlier efforts, we present here an accurate structural solution of the inverse problem by developing a new informationdriven inverse approach (INDIA). The efficacy of the approach is illustrated by choosing amorphous silicon as an example, which is particularly difficult to model using total-energy-based relaxation methods. We demonstrate that, by introducing a subspace optimization technique that sequentially optimizes two objective functions (involving experimental diffraction data, a total-energy functional, and a few geometric constraints), it is possible to produce models of amorphous silicon with very little or no coordination defects and a pristine gap around the Fermi level in the electronic spectrum. The structural, electronic, and vibrational properties of the resulting INDIA models are shown to be fully compliant with experimental data from X-ray diffraction, Raman spectroscopy, differential scanning calorimetry, and inelastic neutron scattering measurements. A direct comparison of the models with those obtained from the Wooten-Winer-Weaire (WWW) approach and from recent high-quality molecular-dynamics simulations is also presented.

MRS Advances, 2019

ABSTRACTWe present an information-based total-energy optimization method to produce nearly defect... more ABSTRACTWe present an information-based total-energy optimization method to produce nearly defect-free structural models of amorphous silicon. Using geometrical, structural, and topological information from disordered tetrahedral networks, we have shown that it is possible to generate structural configurations of amorphous silicon, which are superior than the models obtained from conventional reverse Monte Carlo and molecular dynamics simulations. The new data-driven hybrid approach presented here is capable of producing atomistic models with structural and electronic properties which are on a par with those obtained from the modified Wooten-Winer-Weaire (WWW) models of amorphous silicon. Structural, electronic, and thermodynamic properties of the hybrid models are compared with the best dynamical models obtained from using machine-intelligence-based algorithms and efficient classical molecular dynamics simulations, reported in the recent literature. We have shown that, together wit...