Evaluation of the intramolecular basis set superposition error in the calculations of larger molecules: [n]helicenes and Phe-Gly-Phe tripeptide.
Correlated ab initio calculations on large systems, such as the popular MP2 (or RI-MP2) method, suffer from the intramolecular basis set superposition error (BSSE). This error is typically manifested in molecules with folded structures, characterized by intramolecular dispersion interactions. It can dramatically affect the energy differences between various conformers as well as intramolecular stabilities, and it can even impair the accuracy of the predictions of the equilibrium molecular structures. In this study, we will present two extreme cases of intramolecular BSSE, the internal stability of [n]helicene molecules and the relative energies of various conformers of phenylalanyl-glycyl-phenylalanine tripeptide (Phe-Gly-Phe), and compare the calculated data with benchmark values (experimental or high-level theoretical data). As a practical and cheap solution to the accurate treatment of the systems with large anticipated value of intramolecular BSSE, the recently developed density functional method augmented with an empirical dispersion term (DFT-D) is proposed and shown to provide very good results in both of the above described representative cases.
Valdés
Haydée
H
Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Gilead Sciences Research Center and IOCB and Center for Complex Molecular Systems and Biomolecules, Flemingovo námestí 2, 166 10 Praha 6, Czech Republic.
Klusák
Vojtech
V
Pitonák
Michal
M
Exner
Otto
O
Starý
Ivo
I
Hobza
Pavel
P
Rulísek
Lubomír
L
D005998:Glycine / Q000737:chemistry; D008956:Models, Chemical; D008958:Models, Molecular; D008968:Molecular Conformation; D010455:Peptides / Q000737:chemistry*; D010649:Phenylalanine / Q000737:chemistry; D011083:Polycyclic Compounds / Q000737:chemistry*; D011789:Quantum Theory; D013816:Thermodynamics
D010455:Peptides; D011083:Polycyclic Compounds; C031660:helicenes; D010649:Phenylalanine; D005998:Glycine