Abstract Water confined within one-dimensional (1D) hydrophobic nanochannels has attracted significant interest due to its unusual structure and dynamic properties. As a representative system, water-filled carbon nanotubes (CNTs) are generally studied, but direct observation of the crystal proton transport is difficult for CNTs their poor crystallinity high electron conduction. Here, we report unique water-cluster conduction realized in metal-organic nanotube, [Pt(dach)(bpy)Br] 4 (SO ) ·32H...

Aqueous Na- or K-ion batteries could virtually eliminate the safety and cost concerns raised from Li-ion batteries, but their widespread applications have generally suffered narrow electrochemical potential window (ca. 1.23 V) of aqueous electrolytes that leads to low energy density. Herein, by exploring optimized eutectic systems Na K salts with asymmetric imide anions, we discovered, for first time, room-temperature hydrate melts systems, which are second third alkali metal reported since...

The linear-scaling divide-and-conquer (DC) quantum chemical methodology is applied to the density-functional tight-binding (DFTB) theory develop a massively parallel program that achieves on-the-fly molecular reaction dynamics simulations of huge systems from scratch. functions perform large scale geometry optimization and with DC-DFTB potential energy surface are implemented called DC-DFTB-K. A novel interpolation-based algorithm developed for parallelizing determination Fermi level in DC...

Carbon nanotubes have long been described as rolled-up graphene sheets. It is only fairly recently observed that longitudinal cleavage of carbon nanotubes, using chemical, catalytical and electrical approaches, unzips them into thin strips various widths, the so-called nanoribbons. In contrast, rolling up these flimsy ribbons tubes in a real experiment has not possible. Theoretical studies conducted by Kit et al. demonstrated tube formation through twisting nanoribbon, an idea very different...

We have investigated the growth mechanism of coronene-derived graphene nanoribbons (GNRs) using two different precursors: coronene and a dimer form coronene, so-called dicoronylene (C48H20). For both precursors, formation nanoribbon-like materials inside carbon nanotubes (CNTs) was confirmed by transmission electron microscope observations. Experimental theoretical Raman analysis reveals that samples also encapsulated linearly condensed other oligomers, which can be regarded as analogues to...

Abstract The Criegee intermediates are carbonyl oxides that play critical roles in ozonolysis of alkenes the atmosphere. So far, mid-infrared spectrum only simplest intermediate CH 2 OO has been reported. Methyl substitution produces two conformers 3 CHOO and consequently complicates infrared spectrum. Here we report transient syn - anti -CH CHOO, produced from CHI + O a flow reactor, using step-scan Fourier-transform spectrometer. Guided supported by high-level full-dimensional quantum...

D cdftbmd is a Fortran 90/95 program that enables efficient quantum mechanical molecular dynamics (MD) simulations using divide‐and‐conquer density functional tight‐binding (DC‐DFTB) method. Based on the remarkable performance of previous massively parallel DC‐DFTB energy and gradient calculations for huge systems, code has been specialized to MD simulations. Recent implementations modifications including DFTB extensions, improved computational speed in steps, algorithms initial guess charge...

We present a novel density-functional tight-binding (DFTB) parametrization toolkit developed to optimize the parameters of various DFTB models in fully automatized fashion. The main features algorithm, based on particle swarm optimization technique, are discussed, and number initial pilot applications methodology molecular solid systems presented.

The process of proton diffusion in liquid water was investigated using molecular dynamics (MD) simulations, and the total energy atomic forces were evaluated by divide-and-conquer-type density-functional tight-binding (DC-DFTB) method. effectiveness this approach confirmed comparing computational time clusters with conventional treatments. unit cell employed herein, which contained 523 molecules 1 excess proton, moderately large comparison those used previous studies. reasonable accuracy...

The diffusion of the hydroxide ion in bulk water was examined by linear-scaling divide-and-conquer density-functional tight-binding molecular dynamics (DC-DFTB-MD) simulations using three different-sized unit cells that contained 522, 1050, and 4999 molecules as well one ion. repulsive potential for oxygen-oxygen pair improved iterative Boltzmann inversion, which adjusted radial distribution function DFTB-MD to reference density functional theory-MD one. calculated coefficients Arrhenius...

Predicting pKa values for different types of amine species with high accuracy and efficiency is critical importance the design performance economical solvents in carbon capture storage aqueous solutions. In this study, we demonstrate that density-functional tight-binding-based metadynamics simulations are a promising approach to calculate free energy difference between protonated neutral states amines solution inexpensive computational cost. The calculated were satisfactory agreement...

Abstract Divide-and-conquer-type density-functional tight-binding molecular dynamics simulations of the CO2 absorption process in monoethanolamine (MEA) solution have been performed for systems containing thousands atoms. The formation carbamate anions has widely investigated neutral via ab initio simulations, yet present study is aimed at identifying role hydroxide ions acid-base equilibrium. structural and electronic analyses reveal that ion approaches, Grotthuss-type shuttling,...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTViscoelastic properties of semidilute polystyrene solutionsKunihiro Osaki, Yoshifumi Nishimura, and Michio KurataCite this: Macromolecules 1985, 18, 6, 1153–1157Publication Date (Print):June 1, 1985Publication History Published online1 May 2002Published inissue 1 June 1985https://pubs.acs.org/doi/10.1021/ma00148a019https://doi.org/10.1021/ma00148a019research-articleACS PublicationsRequest reuse permissionsArticle Views238Altmetric-Citations43LEARN...

Combined temperature-programmed desorption and IR studies suggest that absorption cross sections of IR-active vibrations molecules "strongly" bound to single-wall carbon nanotubes (SWCNTs) are reduced at least by a factor 10. Quantum chemical simulations show intensities endohedrally encapsulated dramatically reduced, identify dielectric screening highly polarizable SWCNT sidewalls as the origin such "screening". The observed intensity reduction originates from sizable cancellation adsorbate...

A low-computational-cost algorithm and its parallel implementation for periodic divide-and-conquer density-functional tight-binding (DC-DFTB) calculations are presented. The developed enables rapid computation of the interaction between atomic partial charges, which is bottleneck applications to large systems, by means multipole- interpolation-based approaches long- short-range contributions. numerical errors energy forces with respect conventional Ewald-based technique can be under control...

The present study implemented the divide‐and‐conquer time‐dependent density‐functional tight‐binding (DC‐TDDFTB) code on a graphical processing unit (GPU). DC method, which is linear‐scaling scheme, divides total system into several fragments. By separately solving local equations in individual fragments, method could reduce slow central (CPU)‐GPU memory access, as well computational cost, and avoid shortfalls of GPU memory. Numerical applications confirmed that significantly accelerated...

In this study, divide-and-conquer (DC) based density-functional tight-binding (DFTB) and time-dependent (TD-DFTB) methods were developed using long-range correction (LC), which resolved the underestimation of energy gaps between highest occupied molecular orbital lowest unoccupied orbital. We implemented LC term by entrywise product for effective utilization math kernel library. Test calculations formaldehyde in explicit water molecules demonstrate efficiency method. Furthermore,...

The interaction of acetone with single wall carbon nanotubes (SWCNTs) at low temperatures was studied by a combination temperature programmed desorption (TPD) and dispersion-augmented density-functional-based tight binding (DFTB-D) theoretical simulations. On the basis results TPD study simulations, peaks can be assigned to following adsorption sites: (i) sites energy ∼75 kJ mol−1 (Tdes ∼300 K)—endohedral small diameter (∼7.7 Å); (ii) 40–68 ∼240 K)—acetone on accessible interstitial, groove...

In this study, the divide-and-conquer (DC) method was extended to time-dependent density functional tight-binding (TDDFTB) theory enable excited-state calculations of large systems and is denoted by DC-TDDFTB. The efficient diagonalization algorithms TDDFTB DC-TDDFTB methods were implemented into our in-house program. Test polyethylene aldehyde p-coumaric acid, a pigment in photoactive yellow protein, water demonstrate high accuracy efficiency developed method. Furthermore, (TD)DFTB...

Abstract Aqueous Na‐ or K‐ion batteries could virtually eliminate the safety and cost concerns raised from Li‐ion batteries, but their widespread applications have generally suffered narrow electrochemical potential window (ca. 1.23 V) of aqueous electrolytes that leads to low energy density. Herein, by exploring optimized eutectic systems Na K salts with asymmetric imide anions, we discovered, for first time, room‐temperature hydrate melts systems, which are second third alkali metal...