Large scale polarizability calculations using the approximate coupled cluster model CC2 and MP2 combined with the resolution-of-the-identity approximation

Abstract

We present an implementation of static and frequency-dependent polarizabilities for the approximate coupled cluster singles and doubles model CC2 and static polarizabilities for second-order Mo̸ller-Plesset perturbation theory. Both are combined with the resolution-of-the-identity approximation for electron repulsion integrals to achieve unprecedented low operation counts, input-output, and disc space demands. To avoid the storage of double excitation amplitudes during the calculation of derivatives of density matrices, we employ in addition a numerical Laplace transformation for orbital energy denominators. It is shown that the error introduced by this approximation is negligible already with a small number of sampling points. Thereby an implementation of second-order one-particle properties is realized, which avoids completely the storage of quantities scaling with the fourth power of the system size. The implementation is tested on a set of organic molecules including large fused aromatic ring systems and the C(60) fullerene. It is demonstrated that exploiting symmetry and shared memory parallelization, second-order properties for such systems can be evaluated at the CC2 and MP2 level within a few hours of calculation time. As large scale applications, we present results for the 7-, 9-, and 11-ring helicenes.

Non-additivity of polarizabilities and van der Waals C6 coefficients of fullerenes

“…2,3,[34][35][36][37][38][39][40] The most accurate ab initioᾱ(0) value is 555.27 a.u., 37 obtained using linear-response coupled-cluster single double (LR-CCSD) with a relatively good Sadlej basis set that is however smaller than the one employed in our study. This LR-CCSD calculation with 240 electrons is still one of the largest to-date using coupled-cluster methods and it is not clear that whether the basis employed in these calculations is converged.…”

Cluster perturbation theory. I. Theoretical foundation for a coupled cluster target state and ground-state energies

“…Møller-Plesset perturbation theory (MPPT) is a standard wavefunction method for determining ground-state energies 1,2 and static ground-state molecular properties. [3][4][5][6] The zeroth-order state in MPPT is the Hartree-Fock (HF) state, and the target energy and the target molecular properties are the ones of full configurationinteraction (FCI) wave function calculations. The major drawbacks of MPPT are the following:…”

Accelerating Kohn‐Sham response theory using density fitting and the auxiliary‐density‐matrix method

“…The RI approximation has been used extensively in connection with CC2 molecular properties, and the coupled perturbed Kohn‐Sham equations . It has also been used in TD‐DFT in connection with excitation energies, excited state gradients and frequency‐dependent optical rotation calculations .…”