Hydrogen bonds calculations

Abraham, M. H., Ibrahim, A., Zissimos, A. M., Zhao, Y. H., Comer, J. E., Reynolds, D. Application of hydrogen bonding calculations in property based dmg design. Drug Discov. Today 2002, 7, 1056-1063. 

ST. D. Sokolov (Moscow) By which method was the dispersion term of the energy of the hydrogen bond calculated If it was calculated by London s formula then, first, it should be remembered that it is not applicable near the equilibrium state and, second, that in reality the dispersion interaction (the correlation effects) does not enter additively the energy of the electronic shell... 

It is also well known that the keto-enol equilibrium is modified fundamentally in aqueous solution due to the specific interaction of solvent molecules with the substrates through hydrogen bonds Calculated results summarized in Figure 39a indicate that the keto-enol equilibrium is markedly modified in the bimolecular neutral systems in which each tautomer interacts with one water molecule. In particular, the energy barrier for hydrogen transfer from oxygen to carbon is reduced appreciably, in going from... 

Keywords Hydrogen bond calculation methods calculation strategies basis set effect anhar-... 

Figure 26. Electron-transfer pathway from the molybdenum-pterin center to EAD in xanthine oxidase. Besides the two mercapto groups. Mo is shown coordinated to inorganic sulfur and two oxygen atoms. The total distance between Mo and FAD is 2.9 nm. TTie redox eenters are coupled through a series of covalent bonds, three short van der Waals contacts, and a single hydrogen bond. Calculations were based on the Beratan and Onuchic model (6,7). Coordinates were taken from the PDB, code IFIQ. (See color insert.)...

Compared in Table 4 are the strengths of the CH/O hydrogen bonds calculated for methane and its fluorinated derivatives in complex with water or formaldehyde. " It is noted that the proportion of the electrostatic term is comparable to the ordinary hydrogen bond, whereas contribution from the correlation energy is unimportant. Acetylene, ethylene, and ethane were shown to interact favorably with H2O and NH3. The interaction of CHs... 

Table 13.5. Energy contributions to the interaction energy jjjj in the systemHO-H... OH2 (hydrogen bond) calculated" within the SAPT method electrostatic energy feist, valence repulsion energy f xch induction energy fjmi and dispersion energy (jisp for three 0...0 distances erjuilibrium distance = 3.00 and two distances a little larger medium 3.70 A and large 4.76 A.

Table 13.5. Energy contributions to the interaction energy in the system HO-H... OH2 (hydrogen bond) calculated ...

Table 7 Improvement of the Hydrogen Bond Calculations with H-Bond Linearity Function in Molecular Mechanics Calculations ...

J.-H. Lii and N. L. Allinger. Lone-Pair Directionality in MM4 Hydrogen Bonding Calculation , 1998, in preparation. 

---