An improved generalized AMBER force field (GAFF) for urea


Ozpinar G. , Peukert W., Clark T.

JOURNAL OF MOLECULAR MODELING, cilt.16, ss.1427-1440, 2010 (SCI İndekslerine Giren Dergi) identifier identifier identifier

  • Cilt numarası: 16 Konu: 9
  • Basım Tarihi: 2010
  • Doi Numarası: 10.1007/s00894-010-0650-7
  • Dergi Adı: JOURNAL OF MOLECULAR MODELING
  • Sayfa Sayıları: ss.1427-1440

Özet

We describe an improved force field parameter set for the generalized AMBER force field (GAFF) for urea. Quantum chemical computations were used to obtain geometrical and energetic parameters of urea dimers and larger oligomers using AM1 semiempirical MO theory, density functional theory at the B3LYP/6-31G(d,p) level, MP2 and CCSD ab initio calculations with the 6-311++G (d,p), aug-cc-pVDZ, aug-cc-pVTZ, and aug-cc-pVQZ basis sets, and with the CBS-QB3 and CBS-APNO complete basis set methods. Seven different urea dimer structures were optimized at the MP2/aug-cc-pVDZ level to obtain accurate interaction energies. Atomic partial charges were calculated at the MP2/aug-cc-pVDZ level with the restrained electrostatic potential (RESP) fitting approach. The interaction energies computed with these new RESP charges in the force field are consistent with those obtained from CCSD and MP2 calculations. The linear dimer structure calculated using the force field with modified geometrical parameters and the new RESP charge set agrees well with available experimental data.