arXiv subjects

Marcin Maździarz

Publications and source records attributed to Marcin Maździarz.

At least 19 recordsLinked to original sources

arXiv2025

Mechanical stability conditions for 3D and 2D crystals under arbitrary load

The paper gathers and unifies mechanical stability conditions for all symmetry classes of 3D and 2D materials under arbitrary load. The methodology is based on the spectral decomposition of the fourth-order stiffness tensors mapped to second-order tensors using orthonormal (Mandel) notation, and the verification of the positivity of the so-called Kelvin moduli. An explicit set of stability conditions for 3D and 2D crystals of higher symmetry is also included, as well as a Mathematica notebook that allows mechanical stability analysis for crystals, stress-free and stressed, of arbitrary symmetry under arbitrary loads.

cond-mat.mtrl-sci↗

arXiv2024

Uncertainty of DFT calculated mechanical and structural properties of solids due to incompatibility of pseudopotentials and exchange-correlation functionals

The demand for pseudopotentials constructed for a given exchange-correlation (XC) functional far exceeds the supply, necessitating the use of those commonly available. The number of XC functionals currently available is in the hundreds, if not thousands, and the majority of pseudopotentials have been generated for the LDA and PBE. The objective of this study is to identify the error in the determination of the mechanical and structural properties (lattice constant, cohesive energy, surface energy, elastic constants, and bulk modulus) of crystals calculated by DFT with such inconsistency. Additionally, the study aims to estimate the performance of popular XC functionals (LDA, PBE, PBEsol, and SCAN) for these calculations in a consistent manner.

cond-mat.mtrl-sci↗

arXiv2024

Suitability of available interatomic potentials for Sn to model its 2D allotropes

The suitability of a range of interatomic potentials for elemental tin was evaluated in order to identify an appropriate potential for modeling the stanene (2D tin) allotropes. Structural and mechanical properties of the flat (F), low-buckled (LB), high-buckled (HB), full dumbbell (FD), trigonal dumbbell (TD), honeycomb dumbbell (HD) and large honeycomb dumbbell (LHD) monolayer tin (stanene) phases, were gained by means of the density functional theory (DFT) and molecular statics (MS) calculations with ten different Tersoff, modified embedded atom method (MEAM) and machine-learning-based (ML-IAP) interatomic potentials. A systematic quantitative comparison and discussion of the results are reported.

physics.chem-ph↗

arXiv2024

Atomistic investigation of deformation and fracture of individual structural components of metal matrix composites

This paper focuses on the development of the atomistic framework for determining the lower scale mechanical parameters of single components of a metal matrix composite for final application to a micromechanical damage model. Here, the deformation and failure behavior of NiAl-Al$_2$O$_3$ interfaces and their components, metal and ceramic, are analyzed in depth using molecular statics calculations. A number of atomistic simulations of strength tests, uniaxial tensile, uniaxial compressive and simple shear, have been performed in order to obtain a set of stiffness tensors and strain-stress characteristics up to failure for 30 different crystalline and amorphous systems. Characteristic points on the strain-stress curves in the vicinity of failure are further analyzed at the atomistic level, using local measures of lattice disorder. Numerical results are discussed in the context of composite damage at upper microscopic scale based on images of the fracture surface of NiAl-Al$_2$O$_3$ composites.

cond-mat.mtrl-sci↗

arXiv2023

Transferability of interatomic potentials for germanene (2D germanium)

The capacities of various interatomic potentials available for elemental germanium, with the scope to choose the potential suitable for the modeling of germanene (2D germanium) allotropes were investigated. Structural and mechanical properties of the flat (F), low-buckled (LB), trigonal dumbbell (TD) and large honeycomb dumbbell (LHD) single-layer germanium (germanene) phases, were obtained using the density functional theory (DFT) and molecular statics (MS) computations with Tersoff, MEAM, Stillinger-Weber, EDIP, ReaxFF and machine-learning-based (ML-IAP) interatomic potentials. A systematic quantitative comparative study and discussion of the findings are given.

cond-mat.mtrl-sci↗

arXiv2023

Comment on "Effects of shear methods on shear strengths and deformation modes of two typical transition metal carbides and their unification"

Recently, Chuanying Li, Tao Fu, Xule Li, Hao Hu, and Xianghe Peng in [Phys. Rev. B 107, 224106] investigated the mechanical behavior of cubic HfC and TaC under simple shear (SS) and pure shear (PS) using first-principles calculations. Unfortunately, the paper contains some serious and fundamental flaws in the field of continuum mechanics and nanomechanics. The results presented appear to be qualitatively and quantitatively incorrect, they would be correct if we were in the small/linear deformation/strain regime, which we are not. A correct description therefore requires a finite/nonlinear deformation/strain apparatus.

cond-mat.mtrl-sci↗

arXiv2023

Transferability of force fields for 2D silicon (silicene)

An ability of various interatomic potentials to reproduce the properties of silicene (2D silicon) polymorphs were examined. Structural and mechanical properties of the flat (FS), low-buckled (LBS), trigonal dumbbell (TDS), honeycomb dumbbell (HDS) and large honeycomb dumbbell (LHDS) single-layer silicon (silicene) phases, were obtained using density functional theory (DFT) and molecular statics (MS) calculations with Tersoff, MEAM, Stillinger-Weber, EDIP, ReaxFF, COMB and machine-learning-based (ML-IAP) interatomic potentials. A quantitative systematic comparison and discussion of the results obtained are reported.

cond-mat.mtrl-sci↗

arXiv2022

Comment on "Anisotropic peridynamics for homogenized microstructured materials" by Vito Diana, Andrea Bacigalupo, Marco Lepidi and Luigi Gambarotta [Comput. Methods Appl. Mech. Engrg. 392 (2022) 114704]

Recently, Vito Diana, Andrea Bacigalupo, Marco Lepidi and Luigi Gambarotta proposed an anisotropic continuum-molecular model based on pair potentials for describing the linear behavior of periodic heterogeneous Cauchy materials in the framework of peridynamic theory. Unfortunately, the proposed model for an isotropic material may have zero or even negative shear stiffness and this will be the case for Silicene or Germanene, for example. In addition, 2D symmetries were confused with 3D symmetries, and hence the limits for the Poisson's ratio.

cond-mat.mtrl-sci↗

arXiv2022

Effect of zirconium doping on mechanical properties of $W_{1-x}Zr_xB_2$ on the base of ab initio calculations and magnetron sputtered films

Potentially superhard $W_{1-x}Zr_xB_2$ polymorph hP6-P6$_3$/mmc-$WB_2$ with zirconium doping in the range of x=0.0-0.25 was thoroughly analyzed within the framework of first-principles density functional theory from the structural and mechanical point of view. The obtained results were subsequently compared with properties of material deposited by magnetron sputtering method. All predicted structures are mechanically and thermodynamically stable. Due to theoretical calculations zirconium doping reduces hardness and fracture toughness $K_{IC}$ of $WB_2$. Deposited films are characterized by greater hardness $H_v$ but lower fracture toughness $K_{IC}$. The results of experiments show that not only solid solution hardening is responsible for strengthening of predicted new material but also change of microstructure, Hall-Petch effect and boron vacancies.

cond-mat.mtrl-sci↗

arXiv2020

Molecular potentials for 2D molybdenum disulphide: transferability and performance

An ability of different molecular potentials to reproduce the properties of 2D molybdenum disulphide polymorphs is examined. Structural and mechanical properties, as well as phonon dispersion of the 2H, 1T and 1T' single-layer MoS2 (SL MoS2) phases, were obtained using density functional theory (DFT) and molecular statics calculations (MS) with Stillinger-Weber, REBO, SNAP, and ReaxFF potentials. Quantitative systematic comparison and discussion of the results obtained are reported.

cond-mat.mtrl-sci↗

arXiv2020

Atomistic and mean-field estimates of effective stiffness tensor of nanocrystalline materials of hexagonal symmetry

Anisotropic core-shell model of a nano-grained polycrystal is extended to estimate the effective elastic stiffness of several metals of hexagonal crystal lattice symmetry. In the approach the bulk nanocrystalline material is described as a two-phase medium with different properties for a grain boundary zone and a grain core. While the grain core is anisotropic, the boundary zone is isotropic and has a thickness defined by the cutoff radius of a corresponding atomistic potential for the considered metal. The predictions of the proposed meanfield model are verified with respect to simulations performed with the use of the Large-scale Atomic/Molecular Massively Parallel Simulator, the Embedded Atom Model, and the molecular statics method. The effect of the grain size on the overall elastic moduli of nanocrystalline material with random distribution of orientations is analysed.

physics.comp-ph↗

arXiv2020

New ZrB$_2$ polymorphs: First-principles calculations

Two new hypothetical zirconium diboride (ZrB2) polymorphs: (hP6-P63/mmc space group, no.194) and (oP6-Pmmn-space group, no.59), were thoroughly studied under the first-principles density functional theory calculations from the structural, mechanical and thermodynamic properties point of view. As opposed to the known phase (hP3-P6/mmm-space group, no.191) are not brittle. Knowledge about these new phases can be very useful when doping metal borides with zirconium.

cond-mat.mtrl-sci↗

arXiv2019

Atomistic and mean-field estimates of effective stiffness tensor of nanocrystalline materials of cubic symmetry

Anisotropic core-shell model of a nano-grained polycrystal, proposed recently for nanocrystalline copper, is applied to estimate elastic effective properties for a set of crystals of cubic symmetry. Materials selected for analysis differ in the lattice geometry (face-centered cubic vs. body-centered cubic) as well as the value of a Zener factor: a ratio of two shear moduli defining elastic anisotropy of a cubic crystal. The predictions are verified by means of the atomistic simulations. The dependence of the overall bulk and shear moduli on the average grain diameter is analysed. In the mean-field approach the thickness of the shell is specified by the \emph{cutoff radius} of a corresponding atomistic potential, while the grain shell is isotropic and its properties are identified by molecular simulations performed for very small grains with approximately all atoms belonging to the grain boundary zone. It is shown that the core-shell model provides predictions of satisfactory qualitative and quantitative agreement with atomistic simulations. Performed study indicates that the variation of the bulk and shear moduli with the grain size changes qualitatively when the Zener anisotropy factor is smaller or greater than one.

physics.comp-ph↗

arXiv2019

A comment on "The Computational 2D Materials Database: high-throughput modeling and discovery of atomically thin crystals"

Recently, Sten Haastrup, Mikkel Strange, Mohnish Pandey, Thorsten Deilmann, Per S Schmidt, Nicki F Hinsche, Morten N Gjerding, Daniele Torelli, Peter M Larsen, Anders C Riis-Jensen, Jakob Gath, Karsten W Jacobsen, Jens Jrgen Mortensen, Thomas Olsen and Kristian S Thygesen [2D Mater. 5 (2018) 042002] introduced the Computational 2D Materials Database (C2DB), which organises a variety of structural, thermodynamic, elastic, electronic, magnetic, and optical properties of around 1500 two-dimensional materials distributed over more than 30 different crystal structures. Unfortunately, the work contains serious and fundamental flaws in the field of elasticity and mechanical stability tests what makes it unreliable.

cond-mat.mtrl-sci↗

arXiv2018

Third-order elastic coefficients and logarithmic strain in constitutive and finite element modelling of anisotropic elasticity

Third-order elastic coefficients (TOECs) have been measured experimentally and tabulated with pretty good accuracy since the middle of the previous century. In the classical acoustic measurement method the recalculation of instantaneous stiffness change onto TOECs is based on the use of Green strain. In recent calculations performed by means of atomistic and quantum methods many different strain measures are employed. In result, quite different sets of TOECs can be obtained for the same material. In this paper, it is shown how dramatically the coefficients obtained depend on the choice of strain measure. The known formulas for calculation of the second derivative of a tensor-valued function of tensor variable are corrected. The formulas are essential for the correct analytic calculation of the tangent stiffness matrix in finite element method, among others.

physics.comp-ph↗

arXiv2018

A Molecular Dynamics Study of Self-Diffusion in Stoichiometric B2-NiAl crystals

Self-diffusion parameters in stoichiometric B2-NiAl solid state crystals were estimated by molecular statics/dynamics simulations with the study of required simulation time to stabilise diffusivity results. An extrapolation procedure to improve the diffusion simulation results was proposed. Calculations of volume diffusivity for the B2 type NiAl in the 1224 K to 1699 K temperature range were performed using the embedded atom model potential. The results obtained here are in much better agreement with the experimental results than the theoretical estimates obtained with other methods.

cond-mat.mtrl-sci↗

arXiv2018

Atomistic and mean-field estimates of effective stiffness tensor of nanocrystalline copper

The full elasticity tensor for nano-crystalline copper is derived in molecular simulations by performing numerical tests for a set of generated samples of the polycrystalline material. The results are analysed with respect to the anisotropy degree of the overall stiffness tensor resulting from the limited number of grain orientations and their spatial distribution. The dependence of the overall bulk and shear moduli of an isotropized polycrystal on the average grain diameter is analysed. It is found that while the shear modulus decreases with grain size, the bulk modulus shows negligible dependence on the grain diameter and is close to the bulk modulus of a single crystal. A closed-form mean-field model of effective elastic properties for a bulk nano-grained polycrystal with cubic grains, i.e. made of a material with cubic symmetry, is formulated. In the model all parameters are based on the data for a single crystal and on the averaged grain size without any need for additional fitting. It is shown that the proposed model provides predictions of satisfactory qualitative and quantitative agreement with atomistic simulations.

physics.comp-ph↗

arXiv2018

Anisotropic-cyclicgraphene: A new two-dimensional semiconducting carbon allotrope

Potentially new, single-atom thick semiconducting 2D-graphene-like material, called Anisotropic-cyclicgraphene, have been generated by the two stage searching strategy linking molecular and ab initio approach. The candidate derived from the evolutionary based algorithm and molecular simulations was then profoundly analysed using first-principles density functional theory from the structural, mechanical, phonon, and electronic properties point of view. The proposed polymorph of graphene (rP16-P1m1) is mechanically, dynamically, and thermally stable and can be semiconducting with a direct band gap of 0.829 eV.

cond-mat.mes-hall↗