Modern density functional approximations achieve moderate accuracy at low computational cost for many electronic structure calculations. A mathematical framework for analyzing asymptotic behavior unites both corrections to the gradient expansion of DFT and hyperasymptotics of sums. Simple examples are given for the model problem of orbital-free DFT in one dimension. In some cases, errors can be made

The proteins of the Bcl-2 family are key regulators of apoptosis. They form a complex interaction network in the cytosol and in the cellular membranes, whose outcome determines mitochondrial permeabilization and commitment to death. However, we still fail to understand how the action of the different family members is orchestrated to regulate apoptosis. Here, we combined a quantitative analysis of

Following the development in recent years of progressively accurate approximations to the exchange-correlation functional, the use of density functional theory (DFT) methods to examine increasingly large and complex systems has grown, in particular for solids and other condensed mat- ter systems. However the cost of these calculations is high, often requiring the use of specialist HPC facilities. As

The optical spectra of two-dimensional (2D) periodic systems provide a challenge for time-dependent density-functional theory (TDDFT) because of the large excitonic effects in these materials. In this work we explore how accurately these spectra can be described within a pure Kohn-Sham time-dependent density-functional framework, i.e., a framework in which no theory beyond Kohn-Sham density-functional

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. In this work, we relax a previously imposed positivity constraint, which increased the computational cost and we find that it is safe to do so, except in systems with very few electrons. The constrained minimisation leads invariably to the solution

Virulence-associated glycolipids from Mycobacterium tuberculosis (Mtb) act as effector molecules during infection—in addition to proteins. Upon insertion, they alter host cell membrane properties modifying host functions to impact Mtb survival and disease course. Here we combine tether force experiments and microscopy to reveal, previously unknown, insights on the potential involvement of phosphatidylinositol

Compliance with the Lieb-Oxford bound for the indirect Coulomb energy and for the exchange-correlation energy is investigated for a number of density-functional methods methods based on the adiabatic-connection fluctuation-dissipation (ACFD) theorem to treat correlation. Furthermore, the correlation contribution to the pair density resulting from these methods is compared with highly accurate reference

Two-dimensional covalent organic frameworks (2D COFs) are synthetically diverse, layered macromolecules. Their covalent lattices are thought to confer high thermal stability, which is typically evaluated with thermogravimetric analysis (TGA). However, TGA measures the temperature at which volatile degradation products are formed and is insensitive to changes of the periodic structure of the COF. Here

The recently proposed CAS$\Pi$DFT method combines the reliable description of nondynamic electron correlation with complete active space (CAS) wavefunction and the efficient treatment of dynamic correlation by density functional theory (DFT). This marriage is accomplished by adapting the DFT correlation energy functional modified with the local correction function of the on-top pair density ($\Pi$)

The impact of maculatin 1.1 (Mac1) on the mechanical properties of supported lipid membranes derived from exponential growth phase (EGP) and stationary growth phase (SGP) E. coli lipid extracts was analysed by surface plasmon resonance and atomic force microscopy. Each membrane was analysed by quantitative nanomechanical mapping to derive measurements of the modulus, adhesion and deformation in addition

A cell membrane of Gram-negative bacteria interacting with an antimicrobial peptide represents a complex supramolecular assembly. Fabrication of the models of bacterial cell membranes remains a large experimental challenge. Langmuir-Blodgett and Langmuir-Schaefer (LS-LB) transfer enables deposition of multicomponent asymmetric lipid bilayers onto a gold surface. In this work 1-palmitoyl-2-oleoyl-s

We studied the wing colouration and the compound eyes of Red Admiral butterflies with optical methods. The measured reflectance spectra of the wing and scales of Vanessa atalanta could be quantitatively explained by an optical model of overlapping scales stacked on the wing. We utilized the eyeshine in the compound eye of Vanessa indica to determine the spectral and polarization characteristics of

The many-body problem can in general not be solved exactly, and one of the most prominent approximations is to build perturbation expansions. A huge variety of expansions is possible, which differ by the quantity to be expanded, the expansion variable, the starting point, and ideas how to resum or terminate the series. Although much has been discussed and much has been done, some choices were made

The Kohn-Sham system is the prototypical example of an auxiliary system that targets, in principle exactly, an observable like the electronic density without the need to calculate the complicated many-body wavefunction. Although the Kohn-Sham system does not describe excited-state properties directly, it represents a very successful strategy guideline also for many spectroscopy applications. Here we

We address the problem of bounding rigorously the errors in the numerical solution of the Kohn-Sham equations due to (i) the finiteness of the basis set, (ii) the convergence thresholds in iterative procedures, (iii) the propagation of rounding errors in floating-point arithmetic. In this contribution, we compute fully-guaranteed bounds on the solution of the non-self-consistent equations in the pseudopotential

Gross--Oliveira--Kohn (GOK) ensemble density-functional theory (GOK-DFT) is a time-\textit{independent} extension of density-functional theory (DFT) which allows to compute excited-state energies via the derivatives of the ensemble energy with respect to the ensemble weights. Contrary to the time-dependent version of DFT (TD-DFT), double excitations can be easily computed within GOK-DFT. However, to

The one-body reduced density matrix (1-RDM) of a many-body system at zero temperature gives direct access to many observables, such as the charge density, kinetic energy and occupation numbers. It would be desirable to express it as a simple functional of the density or of other local observables, but to date satisfactory approximations have not yet been found. Deep learning is the state-of the art

A central ambition of the robotics field has been to increasingly miniaturize such systems, with perhaps the ultimate achievement being the synthetic microbe or cell sized machine. To this end, we have introduced and demonstrated prototypes of what we call Colloidal State Machines (CSMs) as particulate devices capable of integrating sensing, memory, energy harvesting as well as other functions onto

Applications of density functional theory (DFT) in computational chemistry rely on an approximate exchange-correlation (xc) functional. However, existing approximations can fail dramatically for open-shell molecules, in particular for transition-metal complexes or radicals. Most importantly, predicting energy-differences between different spin-states with approximate exchange-correlation functionals

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. The expression is based on a constrained search formalism for a supramolecular wavefunction that is forced to leave the diagonal of the many-body density matrix of each fragment unchanged, and is

When a system has evolved far from a ground-state, the adiabatic approximations commonly used in time-dependent density functional theory calculations completely fail in some applications, while giving qualitatively good predictions in others, sometimes even quantitatively so. It is not clearly understood why this is so, and developing practical approximations going beyond the adiabatic approximation

A direct optimization method for obtaining excited electronic states using density functionals is presented. It involves selective convergence on saddle points on the energy surface representing the variation of the energy as a function of the electronic degrees of freedom, thereby avoiding convergence to a minimum and corresponding variational collapse to the ground electronic state. The method is

The majority of angiosperms have flowers with conical epidermal cells, which are assumed to have various functions, such as enhancing the visual signal to pollinators, but detailed optical studies on how conical epidermal cells determine the flower’s visual appearance are scarce. Here we report that conical epidermal cells of Mandevilla sanderi flowers effectively reduce surface gloss, create a velvety

Photonics, the manipulation of light at nanoscale, is a key enabling technology with impact in health and energy applications, among others. In most cases photonics still rely on materials and fabrication methods inherited from other disciplines, usually requiring expensive, time-consuming, and environmentally-unfriendly processes. Recent experiments demonstrated that advanced photonic materials, as

Reflective assemblies of high refractive index organic crystals are used to produce striking optical phenomena in organisms based on light reflection and scattering. In aquatic animals, organic crystal-based reflectors are used both for image-formation and to increase photon-capture. Here we report the characterization of a poorly-documented reflector in the eye of the shrimp L. vannamei lying 150

Quantum mechanical predictive modelling in chemistry and biology is often hindered by the long time scales and large system sizes required of the computational model. Here, we employ the kernel regression machine learning technique to construct an analytical potential, using the Gaussian Approximation Potential software and framework, that reproduces the quantum mechanical potential energy surface

Peacock feathers feature a rich gamut of colours, created by a most sophisticated structural colouration mechanism. The feather barbules contain biophotonic structures consisting of two-dimensionally-ordered lattices of cylindrical melanosomes and air channels embedded in keratin. Here, we study the reflectance characteristics of the various peacock tail feather colours by applying bifurcated-probe-

Existing sensors for gaseous species often degrade their performance because of the loss of the measurement accuracy in the presence of interferences. Thus, new sensing approaches are required with improved sensor selectivity. We are developing a new generation of gas sensors, known as multivariable sensors, that have several independent responses for multi-gas detection with a single sensor. In this

Eggshell is essential for the reproduction of birds since the optical properties of their shells may have an impact on biological functions such as heating and UV protection, recognition by the parents or camouflage. Whereas ultraviolet reflection by some bird eggshells has been recently described, its physical origin remains poorly understood. In this study, we identified a porous structure in the

The prototypical pillared layer MOFs, formed by a square lattice of paddle-wheel units and connected by dinitrogen pillars, can undergo a breathing phase transition by a “wine-rack” type motion of the square lattice. We studied this not yet fully understood behavior using an accurate first principles parameterized force field (MOF-FF) for larger nanocrystallites on the example of Zn_{2}(bdc)_{2}(dabco)

Multiconfiguration pair-density functional theory (MC-PDFT) has previously been applied successfully to carry out ground-state and excited-state calculations. However, because it includes no interaction between electronic states, MC-PDFT calculations in which each state’s PDFT energy is calculated separately can give an unphysical double crossing of potential energy surfaces (PESs) in a region near

Unusual adsorption phenomena, such as breathing and negative gas adsorption (NGA), are rare and challenge our understanding of the thermodynamics of adsorption in deformable porous solids. In particular, NGA appears to break the rules of thermodynamics by exhibiting a spontaneous release of gas accompanying an increase in pressure. This apparent anomaly is in fact due to long-lived metastable states

For a number of optical applications, it is advantageous to precisely tune the refractive index of a liquid. Here, we harness a well-established concept in optics for this purpose. The Kramers-Kronig relation provides physical connection between the spectral variation of the (real) refractive index and the absorption coefficient. In particular a sharp spectral variation of the absorption coefficient

The activity-stability conundrum has long been the Achilles' heel in the design of catalysts, in particular, for electrochemical reactions such as water splitting. Here, we use ab-initio thermodynamics to delineate the surface stoichiometry of a group of perovskite oxides with different activities towards the oxygen evolution reaction (OER), in order to get a measure of their stability under OER operating

Zr(IV) metal-organic frameworks (MOFs) UiO-68 and PCN-57, containing linkers triphenylene dicarboxylate (TPDC) and tetramethyl-triphenylene dicarboxylate (TTDC), respectively, were doped with an H shaped, tetracarboxylate linker that contains a [2]rotaxane molecular shuttle. The new MOFs, UWDM-8 and UWDM-9, contain a [2]rotaxane crossbar spanning the tetrahedral cavities of the fcu topology while the

Plants have various strategies to protect themselves from harmful light. An example of such a protective mechanism is the growth of epicuticular nanostructures, such as a layer of hair or wax crystals. Most nanostructures are optimised to screen UV radiation, as UV light is particularly damaging for cellular tissue. We find that, contrary to the commonly found UV reflectance, the epicuticular wax crystals

The luminescent and proton conductive Pt(II) complex [PtCl(tpy-o-py)]Cl and its HCl adduct [PtCl(tpy-o-pyH)]Cl2 (o-Pt and o-Pt·HCl, respectively; tpy-o-py = 2,2′: 6′,2′′-terpyridine-6′,2′′′-pyridine) were synthesised and their crystal structures, vapochromic behaviour, and proton conduction investigated and compared to those of the para isomers [PtCl(tpy-p-py)]Cl and [PtCl(tpy-p-pyH)]Cl2 (p-Pt and

Metal-Organic Frameworks (MOFs) thanks to their Type V water adsorption isotherm (“S-Shape”) and large water capacity are considered as potential breakthourgh adsorbents for heat-pump applications. In particular Al(OH)-fumarate could enable efficient regeneration at lower temperature than silica-gel which would allow to adress the conversion of waste heat at low temperature such as found in data centers

Molecular adsorption on a surface is a unique way to break the mirror-symmetry of prochiral molecules, and therefore the use of chiral surfaces is an effective strategy for achieving highly selective chiral separation and asymmetric catalytic reactions based on the molecular adsorption with high diastereoselectivity. We have previously reported a porous metal-macrocycle framework (MMF) having an enantiomeric

A three-dimensional (3D) metal–organic framework [Ag(pL2)(CF3SO3)]·2C6H6 (pL2 = 1,3,5-tris(4-ethynylbenzonitrile)benzene), composed of Ag+ and tripodal nitrile ligands, was prepared to enable the investigation of its crystal melting and vitrification behaviors. The guest-free state showed a crystal melting at 271 degC, and the liquid state transformed into a glassy state via cooling. The vitrification

Until now, hues as dynamic as those adorning the Apatura Emperor butterflies have never been encountered in the art world. Unlike and unmatched by the chemical pigments traditionally found on the painter’s palette, the Emperor’s wings are studded with strongly reflecting iridescent scales that are structured like those of the iconic morpho butterflies. The scale ridges act as diffractive multilayers

The existence of correlated disorder in molecular frameworks is an obvious mechanism by which unusual cooperative phenomena might be realised. We show that the use of local-symmetry lowering approaches can allow ostensibly high-symmetry framework structures to harbour exotic disordered states often studied in the context of spin lattice models. These states exhibit strongly cooperative behaviour that

A porous organic cage crystal, α-CC2, shows unexpected adsorption of sulphur hexafluoride (SF6) in its cage cavities, which are formally occluded even to the smallest diatomic gas, H2, according to a pore analysis of the static crystal structure. In situ powder X-ray diffraction (PXRD) experiments provide unequivocal evidence for the presence of (SF6) inside the ‘occluded’ cage voids, pointing to a

To exploit the full potential of metal-organic frameworks as solid adsorbents in water-adsorption applications, many challenges remain to be solved. A more fundamental insight into the properties of the host material and the influence water exerts on them can be obtained by performing molecular simulations. In this work, the prototypical flexible MIL-53(Al) framework is modelled using advanced molecular

Controlling the assembly of molybdenum disulfide (MoS2) layers into static and dynamic superstrucutres can impact on their use in optoelectronics, energy, and drug delivery. Toward this goal, we present a strategy to drive the assembly of MoS2 layers via the hybridization of complementary DNA linkers. By functionalizing the MoS2 surface with thiolated DNA, MoS2 nanosheets were assembled into mulitlayered

The process combining heterogeneous catalysts and DC electric field can achieve high catalytic activities, even under mild conditions (<500 K) with less electrical energy consumption. Hydrogen production by steam reforming of methane, aromatics and alcohol, dehydrogenation of methylcyclohexane, dry reforming of methane, and ammonia synthesis are known to proceed at low temperatures in an electric field

The hydroformylation of 1-hexene with 12 bar of 1:1 H2/CO in the presence of the catalytic system [Rh(acac)(CO)2]/PPh3 was successfully studied by real-time multinuclear high-resolution FlowNMR spectroscopy at 50 °C. Quantitative reaction progress curves that yield rates as well chemo- and regioselectivities have been obtained with varying P/Rh loadings. Dissolved H2 can be monitored in solution to

Metal-organic frameworks (MOFs) provide a suitable platform for stable and efficient heterogeneous photoelectrochemical oxidation catalysis due to their highly ordered structure, large surface area, and synthetic tunability. Herein, a mixed-linker MOF comprising a photosentisizer [Ru(dcbpy)(bpy)2]2+ (bpy = 2,2'-bipyridine, dcbpy = 5,5′-dicarboxy-2,2′-bipyridine) and catalyst [Ru(tpy)(dcbpy)Cl]+ (tpy

Structural vivid colours can arise from the interference of light reflected from structures exhibiting periodicity on scales in the range of visible wavelengths. This effect is observed with light reflected from cell-walls of some plants and exoskeletons of certain insects. Sometimes the colour sequence observed for these structures consists of nearly circular concentric rings that vary in colour from

Supported liquid phase catalysis has great potential to unify the advantages from both, homogeneous and heterogeneous catalysis. Recently, we reported Supported Catalytically Active Liquid Metal Solutions (SCALMS) as a new class of liquid phase catalysts. SCALMS enable high temperature application due to the high thermal stability of liquid metals when compared to supported molten salts or ionic liquids

III-VI post-transition metal chalcogenides (InSe and GaSe) are a new class of layered semiconductors, which feature a strong variation of size and type of their band gaps as a function of number of layers (N). Here, we investigate exfoliated layers of InSe and GaSe ranging from bulk crystals down to monolayer, encapsulated in hexagonal boron nitride, using Raman spectroscopy. We present the N-dependence

Many framework materials such as metal-organic frameworks (MOF) or porous coordination polymers (PCPs) are synthesized as polycrystalline powders, which are too small for structure determination by single crystal X-ray diffraction (SCXRD). Here, we show that a three-dimensional (3D) electron diffraction method, namely continuous rotation electron diffraction (cRED), can be used for ab initio structure

Molecules in gas and liquid states, as well as in solution, exhibit significant and random Brownian motion. Molecules in the solid-state, although strongly immobilized, can still exhibit significant intramolecular dynamics. However, in most framework materials, these intramolecular dynamics are driven by temperature, and therefore are neither controlled nor spatially or temporarily aligned. In recent

The colour purity and versatility of fabrication of one-dimensional photonic crystals (1D PhCs) make them ideal candidates for colorimetric sensing of a variety of analytes. For instance, the detection of bacterial contaminants in food via colorimetric sensors can be highly appealing, as most of the existing detection techniques are in general time-consuming and whose read-out requires specialised