# Arash MostofiImperial College London | Imperial · Department of Materials

Arash Mostofi

MA, MSci, PhD (Cantab)

## About

56

Publications

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7,128

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Citations since 2016

## Publications

Publications (56)

Magic-angle twisted trilayer graphene (MATTG) recently emerged as a highly tunable platform for studying correlated phases of matter, such as correlated insulators and superconductivity. Superconductivity occurs in a range of doping levels that is bounded by van Hove singularities, which stimulates the debate of the origin and nature of superconduc...

In graphene, charged defects break the electron-hole symmetry and can even give rise to exotic collapse states when the defect charge exceeds a critical value which is proportional to the Fermi velocity. In this work, we investigate the electronic properties of twisted bilayer graphene (tBLG) with charged defects using tight-binding calculations. L...

We use an atomistic approach to study the electronic properties of monolayer and bilayer black phosphorus in the vicinity of a charged defect. In particular, we combine screened defect potentials obtained from first-principles linear response theory with large-scale tight-binding simulations to calculate the wave functions and energies of bound acc...

Twisted double bilayer graphene (tDBLG) is a moiré material that has recently generated signiﬁcant interest because of the observation of correlated phases near the magic angle. We carry out atomistic Hartree theory calculations to study the role of electron-electron interactions in the normal state. In contrast to twisted bilayer graphene (tBLG),...

We investigate the chirality of phonon modes in twisted bilayer WSe2 and demonstrate distinct chiral behavior of the K/K′ valley phonons for twist angles close to 0∘ and close to 60∘. In particular, multiple chiral nondegenerate K/K′ valley phonons are found for twist angles near 60∘ whereas no nondegenerate chiral modes are found for twist angles...

We use an atomistic approach to study the electronic properties of monolayer and bilayer black phosphorus in the vicinity of a charged defect. In particular, we combine screened defect potentials obtained from first-principles linear response theory with large-scale tight-binding simulations to calculate the wavefunctions and energies of bound acce...

Twisted double bilayer graphene (tDBLG) is a moire material that has recently generated interest because of the observation of correlated phases near the magic angle. Using an atomistic tight-binding model with self-consistent Hartree interactions, we find that the flat electronic bands of tDBLG are not sensitive to doping, nor to the in-plane vari...

Twisted bilayers of two-dimensional materials, such as twisted bilayer graphene, often feature flat electronic bands that enable the observation of electron correlation effects. In this work, we study the electronic structure of twisted transition metal dichalcogenide homo- A nd heterobilayers that are obtained by combining MoS2, WS2, MoSe2 and WSe...

Starting with twisted bilayer graphene, graphene-based moiré materials have recently been established as a new platform for studying strong electron correlations. In this paper, we study twisted graphene monolayers on trilayer graphene and demonstrate that this system can host flat bands when the twist angle is close to the magic angle of 1.16∘. Wh...

The Open Databases Integration for Materials Design (OPTIMADE) consortium has designed a universal application programming interface (API) to make materials databases accessible and interoperable. We outline the first stable release of the specification, v1.0, which is already supported by many leading databases and several software packages. We il...

We investigate the chirality of phonon modes in twisted bilayer WSe2. We demonstrate distinct chiral behavior of the K/K' valley phonon modes for twist angles close to 0 degrees and close to 60 degrees. Moreover, we discover two sets of well-separated chiral valley modes in moire lattices for angles close to 60 degrees. These emergent moire chiral...

Starting with twisted bilayer graphene, graphene-based moir\'e materials have recently been established as a new platform for studying strong electron correlations. In this paper, we study twisted graphene monolayers on trilayer graphene and demonstrate that this system can host flat bands when the twist angle is close to the magic-angle of 1.16$^\...

Electron-electron interactions are intrinsically long ranged, but many models of strongly interacting electrons only take short-ranged interactions into account. Here, we present results of atomistic calculations including both long-ranged and short-ranged electron-electron interactions for the magnetic phase diagram of twisted bilayer graphene and...

Magic-angle twisted trilayer graphene (MATTG) recently emerged as a highly tunable platform for studying correlated phases of matter, such as correlated insulators and superconductivity. Superconductivity occurs in a range of doping levels that is bounded by van Hove singularities which stimulates the debate of the origin and nature of superconduct...

When calculating the optical absorption spectra of molecular crystals from first principles, the influence of the crystalline environment on the excitations is of significant importance. For such systems, however, methods to describe the excitations accurately can be computationally prohibitive due to the relatively large system sizes involved. In...

Twisted bilayers of two-dimensional materials, such as twisted bilayer graphene, often feature flat electronic bands that enable the observation of electron correlation effects. In this work, we study the electronic structure of twisted transition metal dichalcogenide (TMD) homo- and heterobilayers that are obtained by combining MoS$_2$, WS$_2$, Mo...

Electron-electron interactions are intrinsically long ranged, but many models of strongly interacting electrons only take short-ranged interactions into account. Here, we present results of atomistic calculations including both long-ranged and short-ranged electron-electron interactions for the magnetic phase diagram of twisted bilayer graphene and...

Maximally-localised Wannier functions (MLWFs) are routinely used to compute from first-principles advanced materials properties that require very dense Brillouin zone integration and to build accurate tight-binding models for scale-bridging simulations. At the same time, high-throughput (HT) computational materials design is an emergent field that...

Twisted double bilayer graphene has recently emerged as an interesting moiré material that exhibits strong correlation phenomena that are tunable by an applied electric field. Here we study the atomic and electronic properties of three different graphene double bilayers: double bilayers composed of two AB stacked bilayers (AB/AB), double bilayers c...

Twisted double bilayer graphene has recently emerged as an interesting moir\'e material that exhibits strong correlation phenomena that are tunable by an applied electric field. Here, we study the atomic and electronic properties of three different graphene double bilayers: double bilayers composed of two AB stacked bilayers (AB/AB), double bilayer...

First-principles electronic structure calculations are now accessible to a very large community of users across many disciplines, thanks to many successful software packages, some of which are described in this special issue. The traditional coding paradigm for such packages is monolithic, i.e., regardless of how modular its internal structure may...

Correction for ‘Atomistic QM/MM simulations of the strength of covalent interfaces in carbon nanotube–polymer composites’ by Jacek R. Gołębiowski et al. , Phys. Chem. Chem. Phys. , 2020, 22 , 12007–12014, DOI: 10.1039/d0cp01841d.

First-principles electronic structure calculations are very widely used thanks to the many successful software packages available. Their traditional coding paradigm is monolithic, i.e., regardless of how modular its internal structure may be, the code is built independently from others, from the compiler up, with the exception of linear-algebra and...

We present an overview of the onetep program for linear-scaling density functional theory (DFT) calculations with large basis set (plane-wave) accuracy on parallel computers. The DFT energy is computed from the density matrix, which is constructed from spatially localized orbitals we call Non-orthogonal Generalized Wannier Functions (NGWFs), expres...

Linear‐scaling density functional theory simulation of methylated imogolite nanotubes (NTs) elucidates the interplay between wall‐polarization, bands separation, charge‐transfer excitation, and tunable electrostatics inside and outside the NT‐cavity. The results suggest that integration of polarization‐enhanced selective photocatalysis and chemical...

Understanding the interaction between dopants and semiconductor-oxide interfaces is an increasingly important concern in the drive to further miniaturize modern transistors. To this end, using a combination of first-principles density-functional theory and a continuous random network Monte Carlo method, we investigate electrically active arsenic do...

Author Summary
Investigation of the effects of nanomaterials on biological systems is crucial due to the increasing exposure to nanostructured materials with the growing developments and applications of nanotechnology in everyday life. Nanoparticles have been shown to have an effect on protein structure and interfere with protein self-assembly lead...

Localized Wannier functions provide an efficient and intuitive means by which
to compute dielectric properties from first principles. They are most commonly
constructed in a post-processing step, following total-energy minimization.
Nonorthogonal generalized Wannier functions (NGWFs) [Skylaris et al., Phys.
Rev. B 66, 035119 11 (2002); Skylaris et...

We present an approach to the DFT+U method (Density Functional Theory +
Hubbard model) within which the computational effort for calculation of ground
state energies and forces scales linearly with system size. We employ a
formulation of the Hubbard model using nonorthogonal projector functions to
define the localized subspaces, and apply it to a l...

The electronic ground state of a periodic system is usually described in
terms of extended Bloch orbitals, but an alternative representation in terms of
localized "Wannier functions" was introduced by Gregory Wannier in 1937. The
connection between the Bloch and Wannier representations is realized by
families of transformations in a continuous spac...

We present an implicit solvent model for ab initio electronic structure
calculations which is fully self-consistent and is based on direct solution of
the nonhomogeneous Poisson equation. The solute cavity is naturally defined in
terms of an isosurface of the electronic density according to the formula of
Fattebert and Gygi (J. Comp. Chem. 23, 6 (2...

We investigate a recently developed approach [P. L. Silvestrelli, Phys. Rev. Lett. 100, 053002 (2008); J. Phys. Chem. A 113, 5224 (2009)] that uses maximally localized Wannier functions to evaluate the van der Waals contribution to the total energy of a system calculated with density-functional theory. We test it on a set of atomic and molecular di...

We present a generalized definition of subspace occupancy matrices in ab
initio methods for strongly correlated materials, such as DFT+U and DFT+DMFT,
which is appropriate to the case of nonorthogonal projector functions. By
enforcing the tensorial consistency of all matrix operations, we are led to a
subspace projection operator for which the occu...

We calculate the thermoelectric figure of merit, zT=S2GT/(κl+κe), for p-type Si nanowires with axial Ge heterostructures using a combination of first-principles density-functional theory, interatomic potentials, and Landauer-Buttiker transport theory. We consider nanowires with up to 8400 atoms and twelve Ge axial heterostructures along their lengt...

Linear scaling methods for density-functional theory (DFT) simulations are formulated in terms of localized orbitals in real space, rather than the delocalized eigenstates of conventional approaches. In local-orbital methods, relative to conventional DFT, desirable properties can be lost to some extent, such as the translational invariance of the t...

A robust, user-friendly, and automated method to determine quantum
conductance in disordered quasi-one-dimensional systems is presented. The
scheme relies upon an initial density- functional theory calculation in a
specific geometry after which the ground-state eigenfunctions are transformed
to a maximally-localised Wannier function (MLWF) basis. I...

We present calculations of formation energies of defects in an ionic solid (Al(2)O(3)) extrapolated to the dilute limit, corresponding to a simulation cell of infinite size. The large-scale calculations required for this extrapolation are enabled by developments in the approach to parallel sparse matrix algebra operations, which are central to line...

We present a formulation of the density-functional theory + Hubbard model (DFT+U) method that is self-consistent over the choice of Hubbard projectors used to define the correlated subspaces. In order to overcome the arbitrariness in this choice, we propose the use of non-orthogonal generalized Wannier functions (NGWFs) as projectors for the DFT+U...

ONETEP is an ab initio electronic structure package for total energy calculations within density-functional theory. It combines ‘linear scaling’, in that the total computational effort scales only linearly with system size, with ‘plane-wave’ accuracy, in that the convergence of the total energy is systematically improvable in the manner typical of...

ONETEP is a linear scaling code for performing first-principles total energy calculations within density-functional theory (DFT). The method is based on the density-matrix formulation of DFT and involves the iterative minimization of the total energy with respect to a set of local orbitals and a density kernel. An overview is given of the kernel op...

wannier90 is a program for calculating maximally-localised Wannier functions (MLWFs) from a set of Bloch energy bands that may or may not be attached to or mixed with other bands. The formalism works by minimising the total spread of the MLWFs in real space. This is done in the space of unitary matrices that describe rotations of the Bloch bands at...

The ONETEP program employs the single-particle density matrix reformulation of Kohn-Sham density functional theory to achieve computational cost and memory requirements which increase only linearly with the number of atoms. As the code employs a plane wave basis set (in the form of periodic sinc functions) and pseudopotentials it is able to achieve...

We introduce an alternative approach to the first-principles calculation of NMR shielding tensors. These are obtained from the derivative of the orbital magnetization with respect to the application of a microscopic, localized magnetic dipole. The approach is simple, general, and can be applied to either isolated or periodic systems. Calculated res...

Conventional methods for atomistic simulations bas-ed on density-functional theory (DFT), such as the plane-wave pseudopotential approach, have had an immense impact on the way in which material properties are stud-ied. In spite of this success, the system-size accessible to such techniques is limited because the algorithms scale with the cube of t...

An overview of the ONETEP (Order-N Electronic Total Energy Package) code is presented, focusing on the twin aims of overall linear scaling and controlled accuracy. The method is outlined, including a description of the density-matrix formulation of density-functional theory, and the optimisation procedures for both the density-kernel and the local...

Basis set superposition error (BSSE) in density-functional calculations occurs when the extended Kohn–Sham orbitals are expanded in localised basis sets, but is absent when a plane-wave basis is used. Elimination of BSSE is essential for the accurate description of intermolecular forces. Linear-scaling methods are formulated in terms of local orbit...

We describe the algorithms we have developed for linear-scaling plane wave density functional calculations on parallel computers as implemented in the onetep program. We outline how onetep achieves plane wave accuracy with a computational cost which increases only linearly with the number of atoms by optimising directly the single-particle density...

We present a detailed comparison between ONETEP, our linear-scaling density functional method, and the conventional pseudopotential plane wave approach in order to demonstrate its high accuracy. Further comparison with all-electron calculations shows that only the largest available Gaussian basis sets can match the accuracy of routine ONETEP calcul...

We present ONETEP (order-N electronic total energy package), a density functional program for parallel computers whose computational cost scales linearly with the number of atoms and the number of processors. ONETEP is based on our reformulation of the plane wave pseudopotential method which exploits the electronic localization that is inherent in...

Linear-scaling electronic structure methods are essential for calculations on large systems. Some of these approaches use a systematic basis set, the completeness of which may be tuned with an adjustable parameter similar to the energy cut-off of plane-wave techniques. The search for the electronic ground state in such methods suffers from an ill-c...

We present a novel real space formalism for ab initio electronic structure calculations. We use localized non-orthogonal functions that are expressed in terms of a basis set that is equivalent to a plane-wave basis. As a result, advantages of the plane-wave approach also apply to our method: its applicability to any lattice symmetry, and systematic...

We present a reformulation of the plane-wave pseudopotential method for
insulators. This new approach allows us to perform density-functional
calculations by solving directly for ``nonorthogonal generalized Wannier
functions'' rather than extended Bloch states. We outline the theory on
which our method is based and present test calculations on a va...

We present a method for calculating the kinetic energy of localised functions represented on a regular real space grid. This method uses fast Fourier transforms applied to restricted regions commensurate with the simulation cell and is applicable to grids of any symmetry. In the limit of large systems it scales linearly with system size. Comparison...