Chemical Physics Letters, Vol.376, No.3-4, 403-410, 2003
Single (C-C) and triple (C=C) bond-length dependence of the static electric polarizability and hyperpolarizability of H-C=C-C=C-H
We report an ab initio study of the static electric (hyper)polarizability of diacetylene and its dependence on the single (C-C) and triple (Cequivalent toC) bond length. At the CCSD(T) level of theory we find for the mean dipole polarizability and its derivatives (α) over bar = 49.10 e(2)a(0)(2)E(h)(-1), (partial derivative(α) over bar/partial derivativeR(C-C))(e) = -4.41 and (partial derivative(α) over bar/partial derivativeR(Cequivalent toC))(e) = 34.57 e(2)a(0)E(h)(-1). For the anisotropy Deltaalpha = 54.45 e(2)a(0)(2)E(h)(-1), (partial derivativeDeltaalpha/partial derivativeR (C-C))(e) = -20.42 and (partial derivativeDeltaalpha/partial derivativeR (Cequivalent toC))(e) = 64.56 e(2)a(0)E(h)(-1). The dependence of the mean hyperpolarizability on RC-C and R-Cequivalent toC around the equilibrium is quite distinct. Varying the single bond by DeltaR/A(0) around the equilibrium entails changes of [(γ) over bar (RC-C) - (γ) over bar (R-e)]/e(4)a(0)(4)E(h)(-3) = -3643DeltaR(2) - 184DeltaR(3) + 453DeltaR(4) The mean second hyperpolarizability increases strongly with R-Cequivalent toc around the equilibrium [(γ) over bar (R-Cequivalent toC) - (γ) over bar (R-e)]/e(4)a(0)(4)E(h)(-3) = 22 259DeltaR + 11 293DeltaR(2) + 2384DeltaR(3) + 6445DeltaR(4) (C) 2003 Elsevier B.V. All rights reserved.