Graphynes, two-dimensional layers of sp- and sp2-bonded carbon atoms, have recently received considerable attention because their potential as new Dirac materials. Here, focusing on large surface area, we explore the applicability graphynes lithium ion battery anodes through first-principles density functional calculations. We found that Li energies are in range suitable to be used anodes. Furthermore, maximum composite Li-intercalated multilayer α- γ-graphynes is C6Li3, which corresponds a...

We have performed quantum Monte Carlo calculations to study the cohesion energetics of carbon allotropes, including sp3-bonded diamond, sp2-bonded graphene, sp–sp2 hybridized graphynes, and sp-bonded carbyne. The computed cohesive energies diamond graphene are found be in excellent agreement with corresponding values determined experimentally for graphite, respectively, when zero-point energies, along interlayer binding case included. also that energy graphyne decreases systematically as...

Spectroscopic experiments on molecules embedded in free clusters of liquid helium reveal a number unusual features deriving from the unique quantum behavior this nanoscale matrix environment. The apparent rotation small bosonic He4 is one experimentally most well documented these features. In Focus article, we set phenomenon context experimental and theoretical advances field over last ten years, describe microscopic insight which it has provided into nature dynamic consequences solvation...

The correlation energy of the homogeneous three-dimensional interacting electron gas is calculated using variational and fixed-node diffusion Monte Carlo methods, with trial functions that include backflow three-body correlations. In high-density regime ${(r}_{s}<~5)$ effects dominate over those due to correlations, but relative importance latter increases as density decreases. Since correlations vary nodes function, this leads improved energies in calculations. are comparable found for...

Recently, carbon nanomaterials decorated with Ca atoms as attractors of H2 molecules have been suggested room temperature hydrogen storage media because their large surface area and low weight. However, clustering was found to significantly reduce the capacity Ca–carbon nanostructures. Through first-principles density functional calculations, we explored new allotropes known graphynes for storage. Using equilibrium statistical thermodynamics, that individual Ca-decorated are...

Using the first-principles calculations, we explored feasibility of using graphdiyne, a 2D layer sp and sp2 hybrid carbon networks, as lithium ion battery anodes. We found that composite Li-intercalated multilayer α-graphdiyne was C6Li7.31 calculated voltage suitable for anode. The practical specific/volumetric capacities can reach up to 2719 mAh g−1/2032 cm−3, much greater than values ∼372 g−1/∼818 ∼1117 g−1/∼1589 ∼744 g−1 graphite, graphynes, γ-graphdiyne, respectively. Our calculations...

We investigate the effects of three-body and backflow correlations on ground-state properties two-dimensional electron gas by both variational fixed-node Green's function Monte Carlo methods. It is found that effect dominant over at high density (${\mathit{r}}_{\mathit{s}}$\ensuremath{\sim}1) while they are equal importance lowest considered (${\mathit{r}}_{\mathit{s}}$\ensuremath{\sim}20). With these correlations, we find significant improvements in energies Slater-Jastrow results which...

Excitations of the two-dimensional electron gas, including many-body effects, are calculated with a variational Monte Carlo method. Correlated sampling is introduced to calculate small energy differences between different excitations. The usual pair-product (Slater-Jastrow) trial wave function found lack certain correlations entirely so that backflow correlation crucial. From excitation energies here, we determine Fermi-liquid parameters and related physical quantities such as effective mass...

The local superfluid density around a molecule embedded in ${}^{4}{\mathrm{He}}_{N}$ cluster at low temperatures is analyzed using the path-integral Monte Carlo method. molecular interaction induces nonsuperfluid component within quantum solvation shell whose size determined by range of molecule-helium interaction, and also introduces an anisotropic layering molecule. We show that hydrodynamic analysis internally consistent for $N&gt;50$, can be used to calculate effective rotational...

We present a microscopic quantum theoretical analysis of the nanoscale superfluid properties solvating clusters para-H2 around linear OCS molecule. Path-integral calculations with N=17 molecules, constituting full solvation shell, show appearance significant response to rotation molecular axis at T=0.15 K. This low-temperature is highly anisotropic and drops sharply as temperature increases T approximately 0.3 These provide definitive evidence that an state exists for hydrogen in this layer.

Functionalization of graphdiyne, a two-dimensional atomic layer sp-sp(2) hybrid carbon networks, was investigated through first-principles calculations. Hydrogen or halogen atoms preferentially adsorb on sp-bonded rather than sp(2)-bonded atoms, forming sp(2)- sp(3)-hybridization. The energy band gap graphdiyne is increased from ~0.5 eV to ~5.2 the hydrogenation halogenation. Unlike graphene, segregation adsorbing energetically unfavourable. Our results show that halogenation can be utilized...

The path-integral Monte Carlo technique is applied to study the SF6He39 cluster at low temperatures. method employs as input only pair potentials, number of atoms, and temperature, thus independent trial function bias which can affect calculation structural quantities in variational diffusion Carlo. We thereby obtain an unambiguous answer question location SF6 small clusters (39 He atoms), well temperature dependence structure. found undergo a gradual transition superfluid between 0.625 K...

We present a path integral Monte Carlo (PIMC) methodology for quantum simulation of molecular rotations in superfluid environments such as helium and para-hydrogen that combines the sampling rotational degrees freedom impurity with multilevel Metropolis Bose permutation exchanges solvating species. show how can be applied to evaluation imaginary time correlation functions impurity, from which effective constants extracted. The combined rotation/permutation approach allows first explicit...

We provide definitive theoretical evidence for the onset of superfluidity in small helium clusters doped with molecules at less than one solvation shell, quantitative analysis spectroscopic constants CO2 (4)He(N) terms nonclassical rotational inertia and calculated by path integral methods. find a significant superfluid response N>/=5, essentially unit to rotations around axis partial about an perpendicular N>/=6. This anisotropic is shown be responsible N dependence measured spectra (4)He(N).

We have performed path-integral Monte Carlo calculations to study ${}^{4}$He adsorption on a single graphene sheet. The ${}^{4}$He-substrate interaction was assumed be pairwise sum of the helium-carbon potentials constructed by Carlos and Cole fit helium scattering data from graphite surface. employed both an anisotropic 6-12 Lennard-Jones potential spherical potential. For potentials, first layer has C${}_{1/3}$ commensurate structure at surface density 0.0636 \AA{}${}^{\ensuremath{-}2}$....

Abstract Nanostructured materials, such as zeolites and metal-organic frameworks, have been considered to capture CO 2 . However, their application has limited largely because they exhibit poor selectivity for flue gases low capacity under pressures. We perform a high-throughput screening selective from by using first principles thermodynamics. find that elements with empty d orbitals selectively attract gaseous mixtures pressures (~10 − 3 bar) at 300 K release it ~450 K. binding involves...

On the basis of first-principles calculations, we present exotic geometrical and electronic properties in hydrogenated graphyne, a 2D material sp–sp2 hybrid carbon networks. Hydrogen atoms adsorbed onto sp-bonded can form both sp2- sp3-hybridized bonds exist three different geometries: in-plane, out-of-plane, oblique-plane; this is sharp contrast to graphene, which has only one hydrogenation geometry. The band gaps graphyne vary by ∼3 eV as geometry changes. We also find that change hydrogen...

We report a first-principles study on tuning the electronic band gap of graphyne, consisting two-dimensional sp–sp2 hybrid carbon atoms, by chemical functionalization. Halogen atoms form sp2 hybridization with sp-bonded atoms. This is in sharp contrast to adsorption halogen onto graphene: fluorine graphene sp3 bonds, while chlorine, bromine, and iodine do not any bond graphene. The gaps graphyne increase ∼3 eV as concentration varies, comparable ∼3.4 ∼2.7 engineered hydrogenation...

Rotational absorption spectra of acetylene in superfluid 4He calculated using a path-integral correlation function approach are seen to result an anomalously large distortion constant addition reduced rotational constant, with values excellent agreement recent experiments. Semianalytic treatment the dynamics combined correlated basis function-diffusion Monte Carlo method reveals that this anomalous behavior is due strong coupling higher states molecule roton and maxon excitations 4He,...

We present a detailed analysis of the rotational excitations linear OCS molecule solvated by variable number para-hydrogen molecules (9⩽N⩽17). The effective constant extracted from fit energy levels decreases up to N=13, indicating near-rigid coupling between rotations and motion. Departure rigidity is instead seen for larger clusters with 14⩽N⩽17. Path-integral Monte Carlo calculations show that N dependence can be explained in terms partial superfluid response about an axis perpendicular...

A path integral estimator is presented for the local superfluid response at impurities and interfaces in quantum fluids. The shown to provide a consistent analysis rotational inhomogeneous Bose systems. Applications are made of helium highly structured solvation layers around small linear molecules ($\mathrm{C}{\mathrm{O}}_{2}$ OCS) large planar molecule (phthalocyanine) clusters variable size.

α-Graphyne is a two-dimensional sheet of sp-sp2 hybridized carbon atoms in honeycomb lattice. While the geometrical structure similar to that graphene, triple bonds give rise electronic different from graphene. Similar α-graphyne can be stacked bilayers with two stable configurations, but stackings have very structures: one predicted gapless parabolic bands, and other, tunable band gap which attractive for applications. In order realize applications, it crucial understand stacking more...

Analysis of the helium distribution around a benzene molecule in 4HeN cluster with path integral method shows evidence near complete localization two 4He atoms at positions above and below molecular plane. These are only very weakly coupled to remainder first solvation shell by permutation exchanges, implying that these effectively removed from superfluid solvation. The implications such for spectra clusters discussed.

Path-integral Monte Carlo calculations have been performed to study 4He adsorption on a single C60 molecule. Helium corrugations the fullerene molecular surface are incorporated with 4He-C60 interaction described by sum of all 4He-C interatomic pair potentials. Radial density distributions show layer-by-layer growth first adlayer being located at distance ∼6.3 Å from center The monolayer shows different quantum states as number adatoms N varies. For = 32, we find commensurate solid, each 32...