Themed collection New horizons in density functional theory
List of participants
Concluding remarks for the new horizons in density functional theory Faraday Discussion
The present contribution tries to succinctly review the progress presented during the Faraday Discussions on New horizons in density functional theory that took place online, 2–4 September 2020.
Subsystem density-functional theory for interacting open-shell systems: spin densities and magnetic exchange couplings
Subsystem DFT allows easy access to spin densities for arbitrary broken-symmetry states of radical aggregates.
Introductory lecture: when the density of the noninteracting reference system is not the density of the physical system in density functional theory
We develop expressions for electron density defined through the linear response for general density functional approximations, demonstrating results for orbital functionals and for many-body perturbation theory, and explore the connections to developments in DFT.
Deriving approximate functionals with asymptotics
Could asymtotic expansions make DFT a high accuracy theory?
Cost-effective composite methods for large-scale solid-state calculations
Cost-effective hybrid DFT composite methods allow for large-scale solid-state calculations with small-scale computing resources.
Optical spectra of 2D monolayers from time-dependent density functional theory
Our recently developed pure Kohn–Sham approach for the calculation of optical spectra is applied to the challenging case of 2D monolayers. Our protocol yields a qualitatively good optical spectrum for h-BN, whereas improvements are needed for MoS2.
Improving the exchange and correlation potential in density-functional approximations through constraints
We review and expand on our work to impose constraints on the effective Kohn–Sham (KS) potential of local and semi-local density-functional approximations.
Lieb–Oxford bound and pair correlation functions for density-functional methods based on the adiabatic-connection fluctuation-dissipation theorem
Compliance with the Lieb–Oxford bound is investigated for density-functional methods based on the ACFD theorem to treat correlation. Correlation pair densities resulting from such methods are compared with highly accurate reference values.
Embracing local suppression and enhancement of dynamic correlation effects in a CASΠDFT method for efficient description of excited states
In this work we show that the presence of covalent and ionic configurations in a wavefunction gives rise to spatial regions where the effects of suppression and enhancement of correlation energy, respectively, dominate.
Strategies to build functionals of the density, or functionals of Green’s functions: what can we learn?
The present work examines ways in which model systems are used to design approximate functionals of Green's functions or of the density. It advocates efforts to select and tabulate models that are more flexible than the homogeneous electron gas.
Design of auxiliary systems for spectroscopy
In this contribution, we advocate the possibility of designing auxiliary systems with effective potentials or kernels that target only the specific spectral properties of interest and are simpler than the self-energy of many-body perturbation theory or the exchange–correlation kernel of time-dependent density-functional theory.
A posteriori error estimation for the non-self-consistent Kohn–Sham equations
We address the problem of rigorously bounding the errors in the numerical solution of the Kohn–Sham equations in the pseudopotential approximation. We demonstrate our method by providing band structure diagrams of silicon annotated with the total error.
Weight dependence of local exchange–correlation functionals in ensemble density-functional theory: double excitations in two-electron systems
We discuss the construction of first-rung weight-dependent exchange–correlation density-functional approximations for He and H2 specifically designed for the computation of double excitations within Gross–Oliveira–Kohn-DFT.
Insights into one-body density matrices using deep learning
Deep-learning constraints of the one-body reduced density matrix from its compressibility to enable efficient determination of key observables.
Spin-state dependence of exchange–correlation holes
The exchange–correlation holes of different spin-states are analyzed, as a step towards explicitly spin-state dependent density-functional approximations.
London dispersion forces without density distortion: a path to first principles inclusion in density functional theory
We analyse a path to construct density functionals for the dispersion interaction energy from an expression in terms of the ground state densities and exchange–correlation holes of the isolated fragments.
Developing new and understanding old approximations in TDDFT
In this paper we derive a new expression for the exact exchange–correlation potential from a coupling-constant path integration.
Variational calculations of excited states via direct optimization of the orbitals in DFT
A direct optimization method for obtaining excited electronic states using density functionals is presented.
A machine learning based intramolecular potential for a flexible organic molecule
Here, we employ the kernel regression machine learning technique to construct an analytical potential that reproduces the quantum mechanical potential energy surface of a small, flexible, drug-like molecule, 3-(benzyloxy)pyridin-2-amine.
Multi-state pair-density functional theory
Multi-state Pair-Density Functional Theory (MS-PDFT) gives the correct topology of interacting potential energy surfaces where state-specific calculations fail.
New approaches to study excited states in density functional theory: general discussion
Strong correlation in density functional theory: general discussion
New density-functional approximations and beyond: general discussion
Challenges for large scale simulation: general discussion
About this collection
We are delighted to share with you a selection of the papers associated with a Faraday Discussion on New horizons in density functional theory. More information about the event may be found here: http://rsc.li/dft-fd2020. Density functional theory (DFT) is today’s most widely used method for practical computational electronic structure calculations across chemistry, physics and materials science. It is not only the first alternative for running simulations, but it has also delivered an alternative view-point for thinking about the electronic structure of an enormous range of molecular and solid state systems. Fuelled by a rapid increase in computational power and the advent of linear scaling technologies the systems to which DFT may be applied have become ever larger, more complex and more diverse. This rapid growth in the range of problems that may be subjected to computational study has often highlighted new challenges for DFT methodologies in terms of accuracy, speed and scope, spurring many new developments in the field.
This Faraday Discussion will help to foster new interactions between chemists, physicists, materials scientists and applied mathematicians who develop new density-functional methods and rely on this approach as a key tool in their research. By sharing the latest cutting edge developments and exchanging experience regarding their relative merits the discussion should help bring these new methods to practical application quickly and effectively. The format of the Faraday discussion is an important accelerator for the exchange of ideas in a manner that is not usually possible at conventional meetings.