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6761736 
Journal Article 
Electronic and structural properties of extended-chain compounds and polymers 
Springborg, M; , 
2000 
Yes 
International Journal of Quantum Chemistry
ISSN: 0020-7608
EISSN: 1097-461X 
WILEY-BLACKWELL 
HOBOKEN 
843-858 
WOS:000086229100006 
Results of density functional calculations on infinite, periodic chains are reported. The method that is applied is based on linearized muffin-tin orbitals as basis functions, although the full potential and not only its muffin-tin part is included in the calculations. Special emphasis is put on analyzing the interatomic interactions by means of crystal-orbital overlap or Hamilton populations (COOP and COHP, respectively). As examples of conjugated polymers, hans-polyacetylene and polycarbonitrile are studied. Hero, in particular, the existence of a bond length alternation is discussed. Subsequently, PtS2 (both without and with K counterions) and NbSe3 chains are considered. For the former, the single-chain calculations are supplemented with calculations on the crystalline compounds, and it is shown how single-chain effects are responsible for the structural properties whereas interchain effects have to be included in order to account for all the electronic properties. Parts of the results are explained through an analysis of the COOP and COHP. For NbSe3 the three different structures occurring in the crystalline material are considered, and the implications of our results for the existence of charge density waves as well as the importance of spin-orbit couplings are discussed. Finally, HF as an example of an extended hydrogen-bonded system is examined, and it is demonstrated how the electronic interactions change when the covalent and hydrogen bonds are interchanged as it occurs in charge transport via solitons. (C) 2000 John Wiley & Sons, Inc.