Closing Potential

For conformational energy calculations on structures involving loops (e.g. the loop of gramicidin-S involving only N—C , C —C and peptide bonds, or the loops in proteins involving closure by the S—S bonds of cystine), it is necessary to assure that the loop will close properly to satisfy all the requirements (proper bond distances, bond angles, etc.) of the covalent structure. For this purpose, an empirical loop-closing potential is required. 

For gramicidin-S (Scott et al., 1967), where the loop involves the bonds of the polypeptide backbone, closure of the ring was effected at the C —C bond of an arbitrarily selected residue, together with the following potential function to close the gap  

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Since the relativistic many-body Hamiltonian cannot be expressed in closed potential form, which means it is unbound, projection one- and two-electron operators are used to solve this problem [39], The operator projects onto the space spanned by the positive-energy spectrum of the Dirac-Fock-Coulomb (DFC) operator. In this form, the no-pair Hamiltonian [40] is restricted then to contributions from the positive-energy spectrum and puts Coulomb and Breit interactions on the same footing in the SCF calculations. 

In Fig. 9 the calculated effective potentials are displayed. As can be seen from them, the allowance for the bound ionic states for the amplitudes A = 0 — 1 results in rather insignificant changes in effective potentials, suggesting that the densities of free and bound ions adjust themselves self-consistently to produce very close potentials for different values of A. 

Close potential match between the photopotential and the reqnired storage charging potential. 

In terms of mechanism it means that the polymerization proceeds via the initial formation of the instable anion radical of the bpy ligand (equation 4) leading to an Ru species by the break of the Ru-Cl bond This other instable species (17 electron complex) dimerizes into the dimer is reduced at a close potential. 

The electrochemical behaviour in MeCN of the dicopper(I) complex, [Cu(bddh)J CBF ) ) deserves some comments. Since the solid is white and the solution is colourless, the degree of solvation could not be assessed by spectrophotometry. By cyclic voltammetry some signs of slow decomposition were detected changes in peak potentials within a few hours at any scan rate. The cyclic voltammograms of this complex show sharp cathodic and broad anodic peaks, the broadness of which increases with scan rate. This suggests the possible formation of two copper(II) species, by oxidation at close potentials, with subsequent reduction to the same copper(I) species. Whether this is true or not, whether the dinuclear... 

Hysteresis, asymmetry, and osmotic and electroosmotic effects The entrance of solvent is a physical (osmotic) effect following the electrochemical (Sect. 2) entrance of ions. The solvent is expelled by electroosmosis when the shrinking film approaches to the closing potential (Fuchiwaki et al. 2015). Those two physical effects induce some hysteresis and loop shapes of the coulodynamic responses, generating some minor problems for the control of the actuator movement. 

The fluctuations of anodic current were investigated in a different way by Podesta et al. [20], who showed that in an H2SO4 (1 M) chloride-containing solution a high sulfur-bearing steel (AISI 303) exhibits some anodic current oscillations in a close potential range determined at the active-passive transition region. These oscillations are kept undamped for a particular value of the electrode potential at... 

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