Orbitalfree density functional theory implementation with. I principles of orbitalfree densityfunctional theory basics of densityfunctional theory motivation for ofdft basics of the numerical implementation ii approximations to the kineticenergy functional the thomasfermi approximation the vonweizsacker term linearresponse theory combination of tf and vw the. We consider the thomasfermivon weizsacker energy functional, with the wangteter correction, and present an e. This is a comprehensive overview of stateoftheart computational methods based on orbitalfree formulation of density functional theory completed by the most. Preconditioners and electron density optimization in orbital. Orbitalfree density functional theory for materials research. In the beginning of quantum mechanical density functional theory dft, there was the thomasfermi tf model, which uses the electron density pr a function of only 3 coordinates as the only physical variable. Recent progress in orbitalfree density functional theory. During the last decade, several linearresponse lrbased kedfs have been proposed. Orbitalfree density functional theory implementation with the. Kinetic energy ke approximations are key elements in orbitalfree density functional theory. I principles of orbitalfree densityfunctional theory basics of density functional theory motivation for ofdft basics of the numerical implementation ii approximations to the kineticenergy functional the thomasfermi approximation the vonweizsacker term linearresponse theory combination of tf and vw the. Recent progress in orbitalfree density functional theory downloaded from. This letter proposes a scheme of orbitalfree density functional theory.
Orbitalfree density functional theory for materials. Density functional theory dft is a computational quantum mechanical modelling method used in physics, chemistry and materials science to investigate the electronic structure or nuclear structure principally the ground state of manybody systems, in particular atoms, molecules, and the condensed phases. Irrespective of whether one is using the kohnsham or the orbitalfree approach, one would have to solve the equations in a suitable basis. In computational chemistry, orbitalfree density functional theory is a quantum mechanical approach to electronic structure determination which is based on. A new implementation of density functional theory dft, namely orbital corrected orbital free oo dft, has been developed. It is most closely related to the thomasfermi model. Detailed calibrations of kinetic energy density functionals kedfs and local pseudopotentials were performed to reproduce accurately the energies of several phases of bulk al, as well as the elastic moduli and stacking fault energies of fcc al. Using the projector augmentedwave method paw in combination with realspace methods, we overcome some obstacles faced by other available implementation schemes. The core structure of screw and edge dislocations in fcc al was investigated using orbital free density functional theory ofdft. This letter proposes a scheme of orbitalfree density functional theory ofdft calculation for optimizing electron density based on a semilocal machinelearned ml kinetic energy density functional kedf.
The exact fermi potential yielding the hartreefock electron. Performance of semilocal kinetic energy functionals for. Five linearresponsebased kinetic energy density functionals have been used, one of which has a densitydependent dd response kernel. Using the electron density as the sole variable would reduce the dimensionality of the problem from 3n to 3, thus drastically simplifying quantum mechanical calculations.
Orbitalfree kineticenergy density functional theory. Orbitalfree density functional theory ofdft is a quantum mechanical method in which the energy of a material depends only on the electron density and ionic positions. Citeseerx document details isaac councill, lee giles, pradeep teregowda. Orbitalfree density functional theory using higherorder. An introduction to orbitalfree density functional theory. May 20, 2014 we propose a density functional theory of thomasfermidiracvon weizsacker type to describe the response of a single layer of graphene resting on a dielectric substrate to a point charge or a collection of charges some distance away from the layer. Ofdft is a first principles quantum mechanics method primarily for condensed matter that can be made to scale linearly with system size.
Ionic and electronictransport properties indense plasmas by. Orbitalfree density functional theory the groundstate energy of a charge neutral materials system containing m nuclei and n valence electrons in density functional theory is given by1,7 e. Abstract in the beginning of quantum mechanical densityfunctional theory dft, there was the thomasfermi tf model, which uses the electron density r a function of only 3 coordinates as the only physical variable. Orbital free density functional theory ofdft is both grounded in quantum physics and suitable for direct simulation of thousands of atoms.
Machinelearned kinetic energy density functional and kinetic potential are employed. This is a comprehensive overview of stateoftheart computational methods based on orbitalfree formulation of density functional theory completed by the most recent developments concerning the exact properties, approximations, and interpretations of the relevant quantities in density functional theory. The electron density, which is represented by the square of the linear combination of gaussian functions, is optimized using derivatives. We present a computational scheme for orbitalfree density functional theory ofdft that simultaneously provides access to allelectron values and preserves the ofdft linear scaling as a function of the system size. Orbitalfree density functional theory calculation applying semilocal. With at most two nonselfconsistent iterations, oodft accomplishes.
Read recent progress in orbital free density functional theory by tomasz a wesolowski available from rakuten kobo. Density functional theory dft is a formally exact method to determine the electron density of quantum electrons with out reference to the many body wave equations. We assess several generalized gradient approximations ggas and laplacianlevel metaggas llmgga kinetic energy ke functionals for orbitalfree density functional theory calculations of bulk metals and semiconductors, considering equilibrium distances, bulk moduli, total and kinetic energies, and the electron densities. Kinetic energy ke approximations are key elements in orbital free density functional theory. In orbitalfree density functional theory the kinetic potential kp, the functional derivative of the kinetic energy density functional, appears in the euler equation for the electron density and may be more amenable to simple approximations. This is in fact possible, and it is the goal of orbital free density functional theory ofdft. Orbital free density functional theory ofdft represents a simplification of dft applicable to metallic systems that behave like a freeelectron gas. The exact fermi potential yielding the hartreefock. We present a computational scheme for orbitalfree density functional theory ofdft that simultaneously provides access to. Toward an orbital free density functional theory of transition metals based on an electron density decomposition chen huang department of physics, princeton university, princeton, new jersey 08544, usa emily a. Semilocal approximations for the kinetic energy recent. Orbitalfree density functional theory simulations of.
This is a comprehensive overview of stateoftheart computational methods based on orbitalfree formulation of density. Semilocal pauligaussian kinetic functionals for orbital. Pdf orbitalcorrected orbitalfree density functional theory. Toward an orbitalfree density functional theory of transition metals based on an electron density decomposition chen huang department of physics, princeton university, princeton, new jersey 08544, usa emily a.
We also considered the effects of the pseudopotentials, the vacancy. Recent progress in orbitalfree density functional theory recent. The theories deal with tensors that characterize the oneparticle density matrix and consequently the kinetics of the particles. An alternative firstprinciples quantum mechanics method that is considerably less expensive than ksdft is orbitalfree density functional theory ofdft. The local pseudopotential lpp is an important component of orbitalfree density functional theory, a promising largescale simulation method that can maintain information on a materials. Kohnsham dft in the dft frame work the electron density is found by minimizing the free energy subject to the conservation of the total electron number. The fermi potential, which is defined as that part of the potential that depends on the particles nature, is in this context given as the sum of the pauli potential and the exchange. Orbitalfree density functional theory of outofplane charge screening in graphene. Orbitalfree density functional theory calculation applying. Recent advances in computational chemistry recent progress in orbitalfree density functional theory, pp. This is a comprehensive overview of stateoftheart computational methods based on orbital free formulation of density.
Orbital free density functional theory the groundstate energy of a charge neutral materials system containing m nuclei and n valence electrons in density functional theory is given by1,7 e. The essential challenge in orbital free density functional theory ofdft is to construct accurate kinetic energy density functionals kedfs with general applicability i. Introduction to orbitalfree densityfunctional theory. Densitydecomposed orbitalfree density functional theory for. Download it once and read it on your kindle device, pc, phones or tablets. Pdf on jul 27, 2015, wenhui mi and others published atlas.
The multiscale orbitalfree density functional theorylocal quasicontinuum ofdftlqc method overcomes these problems by using firstprinciples ofdft to capture the atomic interactions while relying upon lqc to evolve the macroscopic system. Ionic and electronictransport properties indense plasmas. However simple local approximations are inaccurate and it has proved very difficult to devise generally accurate nonlocal approximations. Orbital free density functional theory ofdft is an emerging technique for modeling materials bulk and nanoparticles with an accuracy nearing the one of kohnsham dft ksdft and with an. In orbital free density functional theory the kinetic potential kp, the functional derivative of the kinetic energy density functional, appears in the euler equation for the electron density and may be more amenable to simple approximations. Preconditioners and electron density optimization in. We examine some popular algorithms for optimizing the electron density distribution in ofdft, explaining their suitability, benchmarking their performance, and suggesting some.
Realspace formulation of orbitalfree density functional. The essential challenge in orbitalfree density functional theory ofdft is to construct accurate kinetic energy density functionals kedfs with general applicability i. Carter,2 1department of mechanical and aerospace engineering, princeton university, princeton, new jersey 085445263, usa 2program in applied and computational mathematics and andlinger center for energy and the environment. A realspace finitedifference implementation of orbitalfree density functional theory find. We have used density functional theory in an orbitalfree, implementation to calculate the properties of pure fcc al, hcp and bcc mg, and the metastable alloy phase. Current implementations of ofdft employ the planewave basis, the global nature of the basis prevents the efficient use of modern highperformance computer archi tectures. Orbital free density functional theory ofdft is a quantum mechanical method in which the energy of a material depends only on the electron density and ionic positions. Irrespective of whether one is using the kohnsham or the orbital free approach, one would have to solve the equations in a suitable basis. Download citation an introduction to orbitalfree density functional theory given a quantum mechanical system of n electrons and an external potential. Among them, the wanggovindcarter wgc kedf, containing a densitydependent response kernel, is one of the most. Orbital free methods attempt to calculate the noninteracting kinetic energy directly by approximating the universal but unknown kinetic energy density functional. A scheme for orbitalfree density functional theory calculation is implemented. The exact expression for the fermi potential yielding the hartree. Among them, the wanggovindcarter wgc kedf, containing a density dependent response kernel, is one of the most.
The core structure of screw and edge dislocations in fcc al was investigated using orbitalfree density functional theory ofdft. Performing orbitalfree density functional theory calculations. Orbitalfree density functional theory ofdft is both grounded in quantum physics and suitable for direct simulation of thousands of atoms. Improving the orbitalfree density functional theory. Semilocal pauligaussian kinetic functionals for orbitalfree. Chapter 5 orbitalfree kineticenergy density functional theory. Orbitalfree density functional theory of outofplane. Recent progress in orbitalfree density functional theory recent advances in computational chemistry book 6 kindle edition by wesolowski, tomasz a, yan alexander wang, tomasz a wesolowski, yan alexander wang. Orbitalfree density functional theory ofdft this page introduces the orbitalfree dft method in a comprehensive way. We present a computational scheme for orbital free density functional theory ofdft that simultaneously provides access to allelectron values and preserves the ofdft linear scaling as a function of the system size. To date, the use of nonlocal functionals, possibly employing systemdependent parameters, has been considered mandatory in order to obtain satisfactory accuracy for different solidstate systems, whereas semilocal approximations are generally regarded as unfit to this aim. Orbitalcorrected orbitalfree density functional theory. Density functional theory for matter under extreme conditions. This letter proposes a scheme of orbital free density functional theory ofdft calculation for optimizing electron density based on a semilocal machinelearned ml kinetic energy density functional kedf.
By using a local, densitydependent scale function, the total density is decomposed into a highly localized density within covalent bond regions and a. The exact expression for the fermi potential yielding the hartreefock electron density within an orbital. An alternative firstprinciples quantum mechanics method that is considerably less expensive than ksdft is orbital free density functional theory ofdft. Current implementations of ofdft employ the planewave basis, the global nature of the basis prevents the efficient use. Recent advances in computational chemistry recent progress in orbital free density functional theory, pp. In computational chemistry, orbitalfree density functional theory is a quantum mechanical approach to electronic structure determination which is based on functionals of the electronic density. Carter,2 1department of mechanical and aerospace engineering, princeton university, princeton, new jersey 085445263, usa 2program in applied and computational mathematics and andlinger center for energy and the. Carter departments of mechanical and aerospace engineering, program in applied and computational mathematics, and andlinger center for. This article describes the application of ofdft for materials research over roughly the past two decades, highlighting computational studies that would have been impractical or impossible to perform with other techniques. We formulate a variational setting in which the proposed energy functional admits minimizers, both in the case of free graphene layers and under.
Toward an orbitalfree density functional theory of. We assess several generalized gradient approximations ggas and laplacianlevel metaggas llmgga kinetic energy ke functionals for orbital free density functional theory calculations of bulk metals and semiconductors, considering equilibrium distances, bulk moduli, total and kinetic energies, and the electron densities. Based on the same perturbation apqm methods in many. If you are already familiar with the theory and want to learn how to use the orbitalfree gpaw module you can skip the introduction and go directly to the section running the code. The optimized density and electronic energy are evaluated. Use features like bookmarks, note taking and highlighting while reading recent progress in orbitalfree. Using this theory, the properties of a manyelectron system can be determined by using. The thomasfermi model approximates the kinetic energy functional using the ueg as a model. This is in fact possible, and it is the goal of orbitalfree density functional theory ofdft. This is a comprehensive overview of stateoftheart computational methods based on orbital free formulation of density functional theory completed by the most recent developments concerning the exact properties, approximations, and interpretations of the relevant quantities in density functional theory.
Orbital free density functional theory ofdft represents a simplification of dft applicable to metallic systems that behave like a free electron gas. It uses the linear combination of gaussiantype orbital lcgto approach for the selfconsistent solution of the kohnsham ks dft equations. Orbitalfree density functional theory calculations of the. Calculations with this model were inexpensive but yielded poor numerical results due to a lack of. Our orbital free approximation retains the accuracy of the orbital based kohnsham method it reproduces the electron density to high accuracy, while being computationally less expensive and reaching much higher temperatures than are accessible with the kohnsham method. May 12, 2009 in orbital free density functional theory the kinetic potential kp, the functional derivative of the kinetic energy density functional, appears in the euler equation for the electron density and may be more amenable to simple approximations. Nonperiodic finiteelement formulation of orbitalfree. Densitydecomposed orbitalfree density functional theory. Ofdft can be made to scale quasilinearly o nlnn with system size by solving directly for the electron density instead of introducing an auxiliary set of oneelectron orbitals, as is done in. Read recent progress in orbitalfree density functional theory by tomasz a wesolowski available from rakuten kobo. We present profess princeton orbital free electronic structure software, a new software package that performs orbital free density functional theory ofdft calculations. Our orbitalfree approximation retains the accuracy of the orbitalbased kohnsham method it reproduces the electron density to high accuracy, while being computationally less expensive and reaching much higher temperatures than are accessible with the kohnsham method.
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