Evolution of physical properties of conjugated systems

Abstract

Evolution of various physical properties of finite conjugated systems with increasing molecular size is studied using the self-consistent-charge density-functional tight-binding (SCC-DFTB) method. We usually observe a transition from the finite to the infinite regime for surprisingly short molecular chains containing only 20-30 monomer units of cis-butadiene, cyclopentadiene, pyrrole, furan, and thiophene. Such a fast convergence of equilibrium geometries, induced atomic charges, electron densities of states (DOS) and energy gaps, dipole and quadrupole moments, and polarizabilities is particularly striking considering the presence of strong p-conjugation.Convergence in the size evolution of majority of molecular properties of conjugated systems occurs for surprisingly short molecular chains.

Recent Advances in Phosphorus‐Coordinated Transition Metal Single‐Atom Catalysts for Oxygen Reduction Reaction

“…With the addition of nitrogen, M−N x P y sites have more configurations than M−P x sites. The configurations of M−N x P y can be classified into three groups based on the relative positions of N and P: (1) both N and P in the basal plane of graphene; [15,26] (2) both N and P at the edge position; [24] and (3) N in the graphene plane while P as an additional ligand as shown in Figure 2 [25] . All the three groups of M−N x P y sites are thermodynamically stable.…”

“…In the past few years, theoretical and experimental studies have been carried out on the phosphorus coordination active sites, including phosphorus‐coordinated metal (M−P x ) [10–12,19–22] and nitrogen‐phosphorus dual‐coordinated metal (M−N x P y ) [15,23–26] . These catalysts have shown superiority in activity in comparison with N‐coordinated ones.…”

Length dependence of ionization potentials of transacetylenes: Internally consistent DFT/GWapproach

“…There has thus been a search for theoretical methods that can give us accuracy together with feasibility of calculations, spanning a wide range of both inorganic and organic molecular systems [3][4][5][6]. In particular, the class of linear or quasilinear molecular systems-oligomers or polymers-offers a special work space that allows one to concentrate on the length dependence (just one relevant dimension) of the properties of interest: indeed, the dependence and evolution of the IP, the EA, and the electronic gaps with structural characteristics or compositions is a topic of intense study [7][8][9][10][11][12]. For short oligomers in fixed geometries, as for small molecules, these properties can be obtained with high accuracy from high-level quantum-chemistry calculations that go beyond the mean-field approximation, serving as benchmarks for other computational electronic structure approaches [13,14].…”

Spin-orbit force, recoil corrections, and possibleBB¯*andDD¯*Zhao1, Ma2, Zhu3 2014Phys. Rev. D641370View full textAdd to dashboardCite

“…Many theoretical schemes were proposed to explain these XYZ states, including the molecular states [5][6][7][8][9][10], hybrid charmonium [11], tetraquark states [12][13][14][15][16][17], dynamically generated resonances [18]. Among the above schemes, the molecular picture provides a plausible explanation since some XYZ states are very close to the thresholds of a pair of charmed meson.…”