We report first principles density functional calculations for 5,6-dihydroxyindole-2-carboxylic acid (DHICA) and several reduced forms. DHICA and 5,6-dihydroxyindole (DHI) are believed to be the basic building blocks of the eumelanins. Our results show that carboxylation has a significant effect on the physical properties of the molecules. In particular, the relative stabilities and the HOMOLUM...

Representative atomic and molecular systems, including various inorganic and organic molecules with covalent and ionic bonds, have been studied by using density functional theory. The calculations were done with the commonly used exchange-correlation functional B3LYP followed by a comprehensive analysis of the calculated highest-occupied and lowest-unoccupied Kohn-Sham orbital (HOMO and LUMO) e...

In this theoretical study, the role of the side chain moiety of C-terminal residue in influencing the structural and molecular properties of dipeptides is analyzed by considering a series of seven dipeptides. The C-terminal positions of the dipeptides are varied with seven different amino acid residues, namely. Val, Leu, Asp, Ser, Gln, His, and Pyl while their N-terminal positions are kept cons...

Carbon nanotubes are micrometer-long hollow cylinders with nanometer scale radii, and electronic properties strongly depending on their geometrical helicity. As promising tools for building up nanoscale electronic devices, nanotubes also allow one to challenge the well established common theories of mesoscopic physics. Recently, many works of quantum transport in these systems have revealed puz...

Submitted for the MAR10 Meeting of The American Physical Society A hybrid density functional study of double walled armchair SiC nanotubes1 KAPIL ADHIKARI, ASOK RAY, Department of Physics, University of Texas Arlington — As a continuation of our studies of single walled SiC nanotubes,2 we report here a systematic study of double walled armchair type1 SiC nanotubes using the finite cluster appro...

The study of electron transport through single molecules is essential to the development of molecular electronics. Indeed, trends in electronic conductance through organic nanowires have emerged with the increasing reliability of electron transport measurements at the single-molecule level. Experimental and theoretical work has shown that tunneling distance, HOMOLUMO gap and molecular conformat...

The conduction properties of <x,ro-diaminoalkanes and hydrazine bridging gold electrodes are investigated llsing density functio~al theory in combination with Green's function techniques and group theory. We show that more than 99% of the current at lo~ bIas is carried by one channel of A' symmetry whose f~rm is invariant to both the alkane c;h~!n length ~nd realIstic changes of the mJectlOn en...