This paper demonstrates that nanospace engineering of KOH activated carbon is possible by controlling the degree consumption and metallic potassium intercalation into lattice during activation process. High specific surface areas, porosities, sub-nanometer (<1 nm) supra-nanometer (1–5 pore volumes are quantitatively controlled a combination concentration temperature. The process typically leads to bimodal size distribution, with large, approximately constant number pores variable pores. We...

It is shown how appropriately engineered nanoporous carbons provide materials for reversible hydrogen storage, based on physisorption, with exceptional storage capacities (approximately 80 g H2/kg carbon, approximately 50 H2/liter at bar and 77 K). Nanopores generate high (a) by having surface area to volume ratios, (b) hosting deep potential wells through overlapping substrate potentials from opposite pore walls, giving rise a binding energy nearly twice the in wide pores. Experimental case...

We discuss an alternative accurate Monte Carlo method to calculate the ground-state energy and related quantities for Laughlin states of fractional quantum Hall effect in a disk geometry. This approach allows us obtain bulk regime (thermodynamic limit) values various from simulations with small number particles (much smaller than that needed standard approaches).

The p-state clock model in two dimensions is a system of discrete rotors with quasi-liquid phase region T1 < T T2 for p > 4. We show that, 4 and above temperature Teu, all macroscopic thermal averages, such as energy or magnetization, become identical to those the continuous rotor (p = \infty). This collapse thermodynamic observables creates regime extended universality diagram an emergent symmetry, not present Hamiltonian. For \ge 8, starts makes transition at...

Activated carbons are one of promising groups materials for reversible storage hydrogen by physisorption. However, the heat adsorption in such is relatively low, range about 4-8 kJ/mol, which limits total amount adsorbed at P=100 bar to approximately 2 wt % room temperature and 8 77 K. To improve sorption characteristics adsorbing surfaces must be modified either substitution some atoms all-carbon skeleton other elements, or doping/intercalation with species. In this letter we present ab...

The efficient storage and transportation of natural gas is one the most important enabling technologies for use in energy applications. Adsorption porous systems, which will allow high-density fuel under low pressure, possible solutions. We present discuss extensive grand canonical Monte Carlo (GCMC) simulation results adsorption methane into slit-shaped graphitic pores various widths (between 7 angstrom 50 angstrom), at pressures P between 0 bar 360 bar. Our shed light on dependence film...

We derive the long-wavelength elastic theory for quantum Hall smectic state starting from Hartree-Fock approximation. Dislocations in this lead to an effective nematic model $T&gt;0$, which undergoes a disclination unbinding transition phase with algebraic orientational order into isotropic phase. obtain temperatures are qualitative agreement recent experiments have observed large anisotropies of longitudinal resistivities half-filled Landau levels, lending credence liquid crystal...

Breakdown of the quantum Hall effect at high values injected current is explained as a consequence an abrupt formation metallic conduction path from one edge sample to other. Such formed when regions compressible liquid, where long-range disorder potential screened, get connected due strong electric field. Our theory explains various features breakdown and numerical simulations based on yield critical currents consistent with experiment.

Atoms deposited on atomically thin substrates are a playground for exotic quantum many-body physics due to the highly tunable, atomic-scale nature of interaction potentials. The ability engineer strong interparticle interactions can lead emergence collective states matter, not possible in context dilute atomic gases confined optical lattices. While it is known that first layer adsorbed helium graphene permanently locked into solid phase, we motivate, with physically intuitive mean-field...

We aim to understand how the van der Waals force between neutral adatoms and a graphene layer is modified by uniaxial strain electron correlation effects. A detailed analysis presented for three atoms (He, H, Na) ranging from weak moderately strong. show that potential can be significantly enhanced strain, present applications of our results problem elastic scattering graphene. In particular, we find quantum reflection suppressed meaning dissipative inelastic effects near surface become...

The transverse force acting on a quantized vortex in superfluid is problem that has eluded complete understanding for more than three decades. In this Letter I calculate the velocity part of way closely related to Laughlin's argument quantization conductance quantum Hall effect. A combination result, found by Thouless, Ao, and Niu [Phys. Rev. Lett. 76, 3758 (1996)], Galilean invariance shows there cannot be proportional normal fluid velocity.

Since 1999, experiments have shown a plethora of surprising results in the low-temperature magnetotransport intermediate regions between quantum Hall (QH) plateaus: extreme anisotropies observed for half-filling, or re-entrant integer QH effects at quarter filling high Landau levels (LL); even an apparent melting Wigner Crystal (WC) factor ν = 1/7 lowest LL. A large body seemingly distinct experimental evidence has been successfully interpreted terms liquid crystalline phases two-dimensional...

When current is forced through a quantum Hall bar it understood that flows primarily edge states. These represent extra charges in turn produce more widely distributed density falls off rather slowly with distance and then drops rapidly as result of screening by particles beyond the depletion region. We have solved numerically self consistent Schro\ifmmode\ddot\else\textasciidieresis\fi{}dinger equation Hartree approximation for ideal samples small widths sharp boundaries, combined these...

We investigate broken rotational symmetry (BRS) states at half-filling of the valence Landau level (LL). generalize Rezayi and Read's (RR) trial wave function, a special case Jain's composite fermion (CF) functions, to include anisotropic coupling flux quanta electrons, thus generating nematic order in underlying CF liquid. Using Fermi hypernetted-chain method, which readily gives results thermodynamic limit, we determine properties these detail. By using pair distribution static structure...

We present results of molecular dynamics (MD) computer simulations hexane (C6H14) adlayers physisorbed onto a graphite substrate for coverages in the range 0.5 < or = rho 1 monolayers. The molecules are simulated with explicit hydrogens, and is modeled as an all-atom structure having six graphene layers. At above about congruent 0.9 low-temperature herringbone solid loses its orientational order at T(1) 140 +/- 3 K. 0.878, system presents vacancy patches decreases to ca. 100 As coverage...

An exciting development in the field of correlated systems is possibility realizing two-dimensional (2D) phases quantum matter. For a bosons, an example strong correlations manifesting themselves 2D environment provided by helium adsorbed on graphene. We construct effective Bose-Hubbard model for this system which involves hard-core bosons $(U\approx\infty)$, repulsive nearest-neighbor $(V>0)$ and small attractive $(V'<0)$ next-nearest neighbor interactions. The mapping onto accomplished...

We report the results of molecular dynamics simulations a complete monolayer hexane physisorbed onto basal plane graphite. At low temperatures system forms herringbone solid. With increasing temperature, solid-to-nematic liquid-crystal transition takes place at ${T}_{1}=138\ifmmode\pm\else\textpm\fi{}2\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ followed by another ${T}_{2}=176\ifmmode\pm\else\textpm\fi{}3\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ into an isotropic fluid. characterize different phases...

We present the results of molecular-dynamics studies hexane physisorbed onto graphite for eight coverages in range $0.875\ensuremath{\leqslant}\ensuremath{\rho}\ensuremath{\leqslant}1.05$ (in units monolayers). At low temperatures, adsorbate molecules form a uniaxially incommensurate herringbone solid. high coverages, solid consists that are primarily rolled on their side perpendicular to surface substrate. As coverage is decreased, amount molecular rolling diminishes until...