An assessment of polymer band structure calculations

A brief comparison is made of four band structure calculations for the polyethylene chain and it is found that the status of the results bears little relation to the sophistication of the method. A criterion is suggested that may enable one to determine in advance whether this situation is liable to abtain in other systems. It is also observed that claims concerning the power of the band structure approach have not always been in accord with the facts and three main areas are isolated in which the value of such calculations appears to be reasonably unequivocal. In the course of this discussion new results for the PTFE chain are presented.