PMID- 16834032
OWN - NLM
STAT- PubMed-not-MEDLINE
DCOM- 20070801
LR  - 20060712
IS  - 1089-5639 (Print)
IS  - 1089-5639 (Linking)
VI  - 109
IP  - 30
DP  - 2005 Aug 4
TI  - Estimation, computation, and experimental correction of molecular zero-point 
      vibrational energies.
PG  - 6779-89
AB  - For accurate thermochemical tests of electronic structure theory, accurate true 
      anharmonic zero-point vibrational energies ZPVE(true) are needed. We discuss 
      several possibilities to extract this information for molecules from density 
      functional or wave function calculations and/or available experimental data: (1) 
      Empirical universal scaling of density-functional-calculated harmonic 
      ZPVE(harm)s, where we find that polyatomics require smaller scaling factors than 
      diatomics. (2) Direct density-functional calculation by anharmonic second-order 
      perturbation theory PT2. (3) Weighted averages of harmonic ZPVE(harm) and 
      fundamental ZPVE(fund) (from fundamental vibrational transition frequencies), 
      with weights (3/4, 1/4) for diatomics and (5/8,3/8) for polyatomics. (4) 
      Experimental correction of the PT2 harmonic contribution, i.e., the estimate 
      ZPVE(true)PT2 + (ZPVE(fund)expt - ZPVE(fund)PT2) for ZPVE(true). The (5/8,3/8) 
      average of method 3 and the additive correction of method 4 have been proposed 
      here. For our database of experimental ZPVE(true), consisting of 27 diatomics and 
      8 polyatomics, we find that methods 1 and 2, applied to the popular B3LYP and the 
      nonempirical PBE and TPSS functionals and their one-parameter hybrids, yield 
      polyatomic errors on the order of 0.1 kcal/mol. Larger errors are expected for 
      molecules larger than those in our database. Method 3 yields errors on the order 
      of 0.02 kcal/mol, but requires very accurate (e.g., experimental, coupled 
      cluster, or best-performing density functional) input harmonic ZPVE(harm). Method 
      4 is the best-founded one that meets the requirements of high accuracy and 
      practicality, requiring as experimental input only the highly accurate and widely 
      available ZPVE(fund)expt and producing errors on the order of 0.05 kcal/mol that 
      are relatively independent of functional and basis set. As a part of our study, 
      we also test the ability of the density functionals to predict accurate 
      equilibrium bond lengths and angles for a data set of 21 mostly polyatomic 
      molecules (since all calculated ZPVEs are evaluated at the correspondingly 
      calculated molecular geometries).
FAU - Csonka, Gabor I
AU  - Csonka GI
AD  - Department of Inorganic Chemistry, Budapest University of Technology and 
      Economics, H-1521 Budapest, Hungary. csonka@web.inc.bme.hu
FAU - Ruzsinszky, Adrienn
AU  - Ruzsinszky A
FAU - Perdew, John P
AU  - Perdew JP
LA  - eng
PT  - Journal Article
PL  - United States
TA  - J Phys Chem A
JT  - The journal of physical chemistry. A
JID - 9890903
EDAT- 2006/07/13 09:00
MHDA- 2006/07/13 09:01
CRDT- 2006/07/13 09:00
PHST- 2006/07/13 09:00 [pubmed]
PHST- 2006/07/13 09:01 [medline]
PHST- 2006/07/13 09:00 [entrez]
AID - 10.1021/jp0519464 [doi]
PST - ppublish
SO  - J Phys Chem A. 2005 Aug 4;109(30):6779-89. doi: 10.1021/jp0519464.