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Ab initio periodic study of the conformational behavior of glycine helical homopeptides
Author(s) -
Ferrari Anna Maria,
Civalleri Bartolomeo,
Dovesi Roberto
Publication year - 2010
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/jcc.21468
Subject(s) - fock matrix , fock space , conformational isomerism , ab initio , symmetry (geometry) , periodic boundary conditions , chemistry , computational chemistry , matrix (chemical analysis) , basis (linear algebra) , wave function , irreducible representation , crystallography , physics , molecular physics , quantum mechanics , mathematics , boundary value problem , molecule , geometry , chromatography
Representative helicoidal conformations of polyglycine infinite chains have been investigated by using periodic boundary conditions, the B3LYP hybrid functional, and large basis sets, by means of the CRYSTAL code. The exploitation of the helix roto‐translational symmetry permits to optimize at a relatively low cost the structure of systems whose unit cell contains more than 300 atoms, much larger than the one investigated till now. In the present calculations, the helix symmetry is exploited at three levels. First, for the automatic generation of the structure. Second, for the calculation of the one‐ and two‐electron integrals that enter into the Fock matrix definition. Only the irreducible wedge of the Fock matrix is computed. Finally, for the diagonalization of the Fock matrix, where each irreducible representation is separately treated. The efficiency and accuracy of the computational scheme are documented, by considering cells containing up to 47 glycine residues. Results are compared with previous calculations and available experimental data. The role of hydrogen bonding in stabilizing polyglycine conformers is also addressed. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2010