Response electric properties of α-helix polyglycines: A CAM-B3LYP DFT investigation

Dipole moments, electronic polarizabilities and second-order hyperpolarizabilities of glycine oligomers in the alpha-helix conformations have been determined using the long-range corrected CAM-B3LYP functional and the 6-31+G* basis set. The evolution of dipole moment, average polarizability and second-order hyperpolarizability per unit cell as a function of chain length has been explored, giving in the limit of the polymer 4.70 +/- 0.10 D, 32.41 +/- 0.16 a.u. and 5746 +/- 18 a.u., respectively. Interesting linear relationships between the response electric properties, molar volume and softness have been found. The polarizabilities of the oligoglycines are linearly correlated to the second-order hyperpolarizabilities, supporting a three-state model representation of the hyperpolarizabilities. (C) 2013 Elsevier B. V. All rights reserved.