Effect of basis set, electron correlation and hydration on the designing of ternary polypeptides using ant algorithm

The designing of polypeptides with novel conduction properties is important because of the role of proteins in molecular electronics. Ant algorithm which is based on the cooperative interaction between artificial ants has proved to be an effective tool for such designing. It has been used in the present work in combination with simple negative factor counting and inverse iteration methods to study the effect of basis set, electron correlation and hydration on the electronic properties and hence the optimum compositions of polyglycine, polyalanine and polyserine in the most conducting protein chain. The results show clearly that a better basis set and the consideration of correlation decreases the band gap by about 1-3 eV. The optimum solution however remains unaffected. Further, using minimal basis set in the presence of water decreases the band gap by about 2.64 eV and changes the major component of the conducting protein from polyserine to polyalanine.