CCL: Usage of X-ray structure for DFT calculations

 Sent to CCL by: "Stefan  Grimme" [grimme,+,thch.uni-bonn.de]
 Dear Johan Paul,
 indeed the referee is right that any theoretical, isolated molecular structure
 can not directly be compared to those of a molecular crystal because the latter
 is influenced by intermolecular interactions of various type,
 namely Pauli-repulsion, induction, electrostatics, and dispersion
 ("packing forces"). If these (and further thermal) effects are
 significant (rarely) or negligible (the more frequent case) depends on the
 system (and in particular on charges/counter-ions). We recently investigated a
 difficult case by molecular and periodic DFT-D3 calculations:
 J. Moellmann and S. Grimme, Influence of Crystal Packing on an Organometallic
 Ruthenium(IV) Complex Structure: The Right Distance for the Right Reason,
 Organometallics, (2013), 32, 3784-3787. DOI: 10.1021/om400386x
 For a very recent unbiased and fair benchmark of organic molecule gas phase
 structures by experiment and DFT see:
 S. Grimme, M. Steinmetz, Effects of London dispersion correction in density
 functional theory on the structures of organic molecules in the gas phase, Phys.
 Chem. Chem. Phys., (2013), 15, 16031-16042. DOI: 10.1039/c3cp52293h
 Hope this helps
 Stefan