On the basis set superposition error in the evaluation of water dimer interactions

1991 ◽  
Vol 95 (16) ◽  
pp. 6395-6396 ◽  
Author(s):  
Per Olof Aastrand ◽  
Anders Wallqvist ◽  
Gunnar Karlstroem
Keyword(s):  
Water Dimer ◽  
Basis Set ◽  
Basis Set Superposition Error

Counterpoise-Corrected Potential Energy Surfaces of Simple Hydrogen-Bonded Systems

1998 ◽  
Vol 63 (9) ◽  
pp. 1343-1354 ◽  
Author(s):  
Pavel Hobza ◽  
Zdeněk Havlas
Keyword(s):  
Potential Energy Surfaces ◽  
Correlation Energy ◽  
Linear Structure ◽  
Water Dimer ◽  
Basis Set ◽  
Basis Sets ◽  
Basis Set Superposition Error ◽  
Gradient Optimization ◽  
Intermolecular Distances ◽  
Hydrogen Bonded

Geometric and energetic characteristics of various simple hydrogen-bonded complexes (water dimer, hydrogen fluoride dimer, formamide dimer, formic acid dimer, glycine dimer) have been studied by gradient optimization, which a priori eliminates the basis set superposition error (BSSE) by using the counterpoise (CP) method, as well as by the standard gradient optimization. Calculations were done at the Hartree-Fock, correlated MP2 and DFT levels with small- and medium-basis sets. The CP-corrected and standard PESs differ, depending on the theoretical level used. Larger differences were found if the correlation energy was included. Intermolecular distances from the CP-corrected PES are consistently longer, and the respective difference may be significant (≈0.1 A). The stabilization energies obtained from the CP-corrected PES are always larger than those from the standard PES. Optimization at the standard PES might result in a wrong structure. For example, the "quasi-linear" structure of the (HF)2 (global minimum) does not exist at the standard MP2/6-31G** and DFT/B3LYP/6-31G** PESs and it is found only when passing to the respective CP-corrected PESs.

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