Ab initio many-body calculations on infinite carbon and boron-nitrogen chains

摘要

In this paper we report first-principles calculations on the ground-stateelectronic structure of two infinite one-dimensional systems: (a) a chain ofcarbon atoms and (b) a chain of alternating boron and nitrogen atoms. Meanfieldresults were obtained using the restricted Hartree-Fock approach, while themany-body effects were taken into account by second-order M{\o}ller-Plessetperturbation theory and the coupled-cluster approach. The calculations wereperformed using 6-31$G^{**}$ basis sets, including the d-type polarizationfunctions. Both at the Hartree-Fock (HF) and the correlated levels we find thatthe infinite carbon chain exhibits bond alternation with alternating single andtriple bonds, while the boron-nitrogen chain exhibits equidistant bonds. Inaddition, we also performed density-functional-theory-based local densityapproximation (LDA) calculations on the infinite carbon chain using the samebasis set. Our LDA results, in contradiction to our HF and correlated results,predict a very small bond alternation. Based upon our LDA results for thecarbon chain, which are in agreement with an earlier LDA calculationcalculation [ E.J. Bylaska, J.H. Weare, and R. Kawai, Phys. Rev. B 58, R7488(1998).], we conclude that the LDA significantly underestimates Peierlsdistortion. This emphasizes that the inclusion of many-particle effects is veryimportant for the correct description of Peierls distortion in one-dimensionalsystems.