Evaluating First-Order Molecular Properties of Delocalized Ionic or Excited States in Molecular Aggregates by Renormalized Excitonic Method

In the past few years,the renormalized excitonic model(REM)approach was developed as an efficient low-scaling ab initio excited state method,which assumes the low-lying excited states of the whole system are a linear combination of various single monomer excitations and utilizes the effective Hamiltonian theory to derive their couplings.In this work,we further extend the REM calculations for the evaluations of first-order molecular properties(e.g.charge population and transition dipole moment)of delocalized ionic or excited states in molecular aggregates,through generalizing the effective Hamiltonian theory to effective operator representation.Results from the test calculations for four different kinds of one dimensional(1D)molecular aggregates(ammonia,formaldehyde,ethylene and pyrrole)indicate that our new scheme can efficiently describe not only the energies but also wavefunction properties of the low-lying delocalized electronic states in large systems.

Evaluation of flow behavior in copper electro-refining cell with different inlet arrangements

The arrangement of electrolyte inlet in the copper electro-refining(ER)cell has a great influence on the local flow field,which affects the distribution of electrical current density in consequence.In order to understand the complicated phenomena ofelectrolyte flow behavior in vertical counter electrodes in full-scale copper ER cell,the three-dimensional computational fluiddynamics(CFD)models with four different arrangements of electrolyte inlets,i.e.,single inlet(SI),central bottom inlets(CBI),topside interlaced inlets(TII),and bottom side interlaced inlets(BII),were established to simulate the flow behavior.Simulation resultshave revealed that the parallel injection devices help to improve the electrolyte velocity between electrodes,and while the relativerange of electrolyte velocity in CBI exceeds that of TII and BII,which is more than4times,indicating its severer unequal flowdistribution.Meanwhile,the average velocity of electrolyte in BII is4times larger than that of SI due to its higher turbulenceintensity.Generally,one of the efficient ways to supply fresh copper solution rapidly and uniformly into the inter-electrode space is toadapt the arrangement of BII.By utilizing such an arrangement,the electro-refining under high electrical current density is possible,and the productivity can be increased in sequence.

Axial ligands tailoring the ORR activity of cobalt porphyrin

In an effort to provide visualization and understanding to the electronic ‘‘push effect' of axial ligands on the catalytic activity of cobalt macrocyclic molecules, we design a simple model system involving an[5,10,15,20-tetrakis(4-methoxyphenyl)porphyrin]cobalt(II)(TMMPCo) monolayer axially-coordinated on thiol ligand modified Au electrode and explore the activity of the axial-ligand coordinated TMPPCo toward oxygen reduction reaction(ORR) in acidic medium. Three different ligands, with a decreasing order of coordinating ability as: 4-mercaptopyridine(MPy) > 4-aminothiolphenol(APT) > 4-mercaptobenzonitrile(MBN) are used and a maximum difference in ORR onset potential of 80 mV is observed between the MPy(highest onset potential) and MBN systems(lowest onset potential). The ORR activity of TMPPCo increases with the increase in binding strength of the axial ligand. A detailed mechanism study reveals that ORR on the three ligand coordinated TMPPCo systems shares the same2-electron mechanism with H2 O2 as the terminal product. Theoretical calculation into the structure of the ligand coordinated cobalt porphyrins uncovers the variation in atomic charge of the Co(II) center and altered frontier molecular orbital distribution among the three ligand systems. Both properties have great influence on the back-bonding formation between the Co(II) center and O2 molecules, which has been suggested to be critical toward the O2 adsorption and subsequent activation process.