Wydział Chemii

Mingzhu Sheng

Filippo Silvestrini

Małgorzata Biczysko

Cristina Puzzarini

2021

Journal of Physical Chemistry A

125

9099-9114

10.1021/acs.jpca.1c06993

Naukowa

Angielski

Artykuł

The structures, relative stabilities, and vibrational wavenumbers of the two most stable conformers of serine, stabilized by the O−H···N, O−H···OC and N−H···O−H intramolecular hydrogen bonds, have been evaluated by means of state-of-the-art composite schemes based on coupled-cluster (CC) theory. The so-called “cheap” composite approach (CCSD(T)/(CBS+CV)MP2 ) allowed determi-nation of accurate equilibrium structures and harmonic vibrational wavenumbers,also pointing out significant corrections beyond the CCSD(T)/cc-pVTZ level.These accurate results stand as a reference for benchmarking selected hybrid and double-hybrid, dispersion-corrected DFT functionals. B2PLYP-D3 and DSDPBEP86 in conjunction with a triple-ζ basis set have been confirmed as effective methodologies for structural and spectroscopic studies of medium-sized flexible biomolecules, also showing intramolecular hydrogen bonding. These best perform-ing double-hybrid functionals have been employed to simulate IR spectra by means of vibrational perturbation theory, also considering hybrid CC/DFT schemes. Thebest overall agreement with experiment, with mean absolute error of 8 cm−1 , has been obtained by combining CCSD(T)/(CBS+CV)MP2 harmonic wavenumbers with B2PLYP-D3/maug-cc-pVTZ anharmonic corrections. Finally, a composite scheme entirely based on CCSD(T) calculations (CCSD(T)/CBS+CV) has been employed for energetics, further confirming that serine II is the most stable conformer, also when zero-point vibrational energy corrections are included.

Basis sets, Composites, Molecular structure, Peptides and proteins, Quantum mechanics

http://dx.doi.org/10.1021/acs.jpca.1c06993

https://www.acs.org/content/acs/en.html