The electrical conductivity and gas-sensing characteristics of individual sheets partially reduced graphene oxide are studied, the results display a strong dependence on chosen reduction method. Three procedures considered here: thermal, chemical, combined chemical/thermal approach. Samples treated by highest whereas thermally samples fastest response times. chemo-resistive to water vapor adsorption is well fit linear driving force model. upon exposure measured as function gated electric...

Coupled quantum mechanical/molecular mechanical (QM/MM) calculations were used to study the effects of large defects and cracks on properties carbon nanotubes graphene sheets. The semi-empirical method PM3 was treat QM subdomains a Tersoff-Brenner potential for molecular mechanics; some also done using density functional theory (DFT). Scaling so that modulus overall stress-strain behavior MM models matched quite closely essential obtaining meaningful coupled properties. numerical results...

Many methods for correcting harmonic partition functions the presence of torsional motions employ some form one-dimensional treatment to replace contribution a specific normal mode. However, torsions are often strongly coupled other degrees freedom, especially and low-frequency bending motions, this coupling can make assigning modes problematic. Here, we present new class methods, called multi-structural (MS) that circumvents need such assignments by instead adjusting results correction...

Molecular mechanics (MM) calculations together with coupling methods bridging MM and finite crystal elasticity are employed to simulate the fracture of defected carbon nanotubes (CNTs) compare available experimental results. The modified second generation Brenner potential (MTB-G2) is adopted in calculations. Our show fair agreement quantum mechanical (QM) benchmarks, indicate that one- two-atom vacancies reduce strength CNTs by $20%--33%$ (whereas QM predict $14%--27%$), but these strengths...

A hierarchical family of analytical Born–Oppenheimer potential energy surfaces has been developed for the H+H2 system. Ab initio calculations near full configuration interaction (FCI) quality (converged to within ≈1 μEh) were performed a set 4067 configurations with aug-cc-pVDZ, aug-cc-pVTZ, and aug-cc-pVQZ basis sets. The complete (CBS) limit energies obtained using highly accurate many-body extrapolation scheme. Surfaces fitted estimated CBS limit, as well sets robust new functional form....

Practical approximation schemes for calculating partition functions of torsional modes are tested against accurate quantum mechanical results H(2)O(2) and six isotopically substituted hydrogen peroxides. The classified on the basis type amount information that is required. First, approximate one-dimensional hindered-rotator benchmarked exact torsion obtained by eigenvalue summation. methods in this stage include only require equilibrium geometries frequencies, also barrier heights internal...

The neutral muonic helium atom may be regarded as the heaviest isotope of hydrogen atom, with a mass ~4.1 atomic units ((4.1)H), because negative muon almost perfectly screens one proton charge. We report reaction rate (4.1)H (1)H(2) to produce (4.1)H(1)H + (1)H at 295 500 kelvin. experimental constants are compared predictions accurate quantum-mechanical dynamics calculations carried out on an Born-Huang potential energy surface and previously measured (0.11)H (where is shorthand for...

New experimental and theoretical rate constants for two isotopologs of the simplest chemical reaction, H+H2-->H2+H, are presented. The results obtained using accurate quantum dynamics with a converged Born-Oppenheimer potential energy surface include non-Born-Oppenheimer corrections. new experiments carried out shock tube complement earlier investigations over very large T range, 167 to 2112 K. Experiment theory now agree perfectly, within error, bringing this 75-year-old scientific problem...

Angular distributions and time-of-flight spectra for the reaction Cl + H 2 → HCl obtained from a high-resolution, crossed-molecular beam experiment were compared to differential cross sections calculated by both converged quantum mechanical scattering quasi-classical trajectory methods. Good agreement was found between experimental results each theoretical prediction. The demonstrate that excellent can be state-of-the-art simulations experiments detailed dynamical properties of this...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAb Initio Chemical Kinetics: Converged Quantal Reaction Rate Constants for the D + H2 SystemSteven L. Mielke, Gillian C. Lynch, Donald G. Truhlar, and David W. SchwenkeCite this: J. Phys. Chem. 1994, 98, 33, 8000–8008Publication Date (Print):August 1, 1994Publication History Published online1 May 2002Published inissue 1 August 1994https://pubs.acs.org/doi/10.1021/j100084a014https://doi.org/10.1021/j100084a014research-articleACS PublicationsRequest...

Carbon nanotubes (CNTs) can undergo collapse from their customary cylindrical configurations to ribbons. The energy minima corresponding these two states are identified using either atomistic molecular mechanics or the theory of finite crystal elasticity with reduced dimensionality. minimum path between is found nudged elastic band reaction-pathway sampling scheme. energetics CNT explored for both single- and multi-walled CNTs as well small bundles. process has a strong diameter dependence,...

We present quantal reaction rate coefficients obtained from well-converged cumulative probabilities calculated by an algebraic variational method for total angular momentum J in the range 0−6 and separable-rotation approximation ≠ 6. These results are used to test transition state theory calculations with optimized multidimensional tunneling contributions compared experiment.

The validity of the quasiclassical trajectory surface hopping method is tested by comparison against accurate quantum dynamics calculations. Two versions method, one including electronic coherence between hops and neglecting this effect, are applied to electronically nonadiabatic quenching processes Na(3p)+H2(v=0,j=0 or 2)→Na(3s)+H2(v′,j′). They found agree well, not only for probabilities final-state distributions, but also collision lifetimes statistics, demonstrating that important...

Two approaches, the outgoing wave variational principle (OWVP) and R-matrix propagation (RMProp), are presented for quantum dynamics calculations of inelastic scattering in systems involving two coupled potential energy surfaces (PES). The formalisms applied to Na(3p 2P) collisions with H2 at a total 2.426 eV zero unit angular momentum. This provides challenging test case because accessible region excited-state surface intersects ground-state conically involves H–H internuclear distances...

The neutral muonic helium atom (4)Heμ, in which one of the electrons He is replaced by a negative muon, may be effectively regarded as heaviest isotope hydrogen atom, with mass 4.115 amu. We report details first muon spin rotation (μSR) measurements chemical reaction rate constant (4)Heμ molecular hydrogen, + H(2) → (4)HeμH H, at temperatures 295.5, 405, and 500 K, well μSR measurement hyperfine coupling high pressures. experimental constants, k(Heμ), are compared predictions accurate...

Multireference configuration interaction (MRCI) calculations of the Born-Oppenheimer diagonal correction (BODC) for H(3) were performed at 1397 symmetry-unique configurations using Handy-Yamaguchi-Schaefer approach; isotopic substitution leads to 4041 DH(2) mass combination. These results then fit a functional form that permits calculation BODC any combination isotopes. Mean unsigned fitting errors on test grid not included in process 0.14, 0.12, and 0.65 cm(-1) H(3), DH(2), MuH(2)...

In this paper we report angular distributions and time-of-flight spectra for the Cl+H2→HCl+H Cl +D2→DCl+D reactions at 5.85 kcal mol−1 6.3 6.4 collision energies, respectively, obtained from high-resolution crossed molecular beam experiments. addition, quasiclassical trajectory (QCT) quantum mechanical (QM) dynamical calculations have been carried out these on G3 potential energy surface (T. C. Allison et al., J. Phys. Chem., 1996, 100, 13575). Reaction probabilities, integral differential...

Using an isomorphism of Coalson, we transform five different discretized path integral (DPI) methods into Fourier (FPI) schemes. This allows even-handed comparison these to the conventional and partially averaged FPI as well a new method. It also us apply DPI simple highly effective perturbative correction scheme (previously presented for methods) account error due retaining only finite number terms in numerical evaluation propagator. We find that all cases corrections can be extrapolated...