CCL:G: How to consider charge on particular atom -lithium

 Sent to CCL by: "N. Sukumar" [nagams]=[rpi.edu]
 "why are Bader charges thought to be so bad and unacceptable?"
 Bader charges are thought to be so "bad and unacceptable" because
 people
 are so used to thinking in terms of point charges or classical
 ball-and-stick type spherical "atoms". Bader's atoms-in-molecules are,
 in
 general, very far from spherical. Thus the electron population in an AIM
 or the atomic monopole moment (nuclear charge minus the electron
 population) will not, on its own, reproduce the electrostatic potential
 or any other physical property. However with inclusion of higher
 multipole moments the Bader atoms DO reproduce the electrostatic
 potentials and other physical effects.
 Whitehead, et al ?Transferable Atom Equivalent Multi-Centered Multipole
 Expansion Method? J. Comp. Chem. 24, 512-529 (2003)
 N. Sukumar
 Professor of Chemistry
 Shiv Nadar University, India
 ----------------------------
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 ==============Original message text===============
 On Tue, 11 Feb 2014 15:49:29 EST "Salter-Duke, Brian James
 brian.james.duke##gmail.com" wrote:
 Sent to CCL by: "Salter-Duke, Brian James "
 [brian.james.duke-x-gmail.com]
 I do not want to address how the various methods work in practice, as I
 do not have the experience. I do however want to make a general point
 and then ask a question.
 Mulliken charges are not basis set independent as they depend on the
 basis functions we happen to use on each atom. As another poster
 commented, if we use a one centre complete basis the method puts all the
 charge on that atom. Long ago there was a set of one-centre expansion
 calculations on simple systems such as methane. There are no basis
 functions on the hydrogen atoms. The Mulliken charges are C(4-) and
 H(+). If we used basis functions centered only on the H atoms we would
 get C(4+) and H(-). Mulliken charges do not have a basis set limit. Too
 often we use methods to interpret wave functions that do not have a
 basis set limit. I suggest we stop doing that and use methods that do,
 just as we have energies that do. We often extrapolate to that energy
 limit and we should extrapolate to limits for other properties, even
 when they are not observable properties such as charges.
 As others have shown many other methods can reduce the sensitivity of
 NPA charges to basis-set, but they still do not properly have a basis
 set limit.
 Bader charges depend on the basis set only in the sense that the density
 depends on the basis set. They do have a proper basis set limit. They
 are obtained by defining the boundaries of each atom and then
 integrating over the atoms. The AIM method of getting those boundaries
 seems soundly based. Nobody, I think, has come up with a better method.
 So why are Bader charges thought to be so bad and unacceptable. Has that
 question been properly considered and analysed?
 Brian Duke.
 On Tue, Feb 11, 2014 at 10:09:02AM -0500, Tian Lu sobereva-x-sina.com wrote:
 >
 > Sent to CCL by: "Tian  Lu" [sobereva/./sina.com]
 > Hi,
 >
 > AFAIK, there is only one public program can realize Hirshfeld-I, namely
 HiPart (http://molmod.ugent.be/software/).
 > Another modified Hirshfeld-based method alternative to Hirshfeld-I is
 > atomic dipole moment corrected Hirshfeld (ADCH) population method,
 > which is the one I highly recommend, see J. Theor. Comp. Chem., 2012,
 > 11: 163-183. ADCH charges have much better reproducibility for
 > electrostatic potential than Hirshfeld charges, and the molecular
 > dipole moment can be even exactly reproduced. ADCH has been
 > implemented in Multiwfn program (http://Multiwfn.codeplex.com, see> Section 4.7.2 of its
 manual for example).
 > NPA charges (also known as NBO charges) are also nice choice. In fact
 > they are not explicitly dependent on but only indirectly dependent on
 > the basis-set, because the original basis functions will be first
 > transformed to natural atomic orbitals before performing natural
 > population analysis, this step conspicuously reduces the sensitivity
 > of NPA charges to basis-set. According to my experiences, the relative
 > sensitivity to basis-set is Mulliken>=Lowdin>>NPAAIMcharges by
 fitting
 > ESP (MK,CHELPG,etc.) >= HirshfeldADCH.
 > Personally I don't recommend using AIM charges, since calculating AIM
 > charges is usually time-consuming, and their reproducibility for
 > observable quantities are quite poor.
 > A comprehensive comparison of atomic charges can be found in Acta
 > Phys.-Chim. Sinica, 2011, 28: 1-18
 > (http://www.whxb.pku.edu.cn/EN/abstract/abstract27818.shtml)
 >
 > Tian Lu
 >
 >
 >
 >
 > ----- Original Message -----
 > > From: "Susi Lehtola susi.lehtola]![alumni.helsinki.fi"
 <owner-chemistry+/-ccl.net>
 > To: "Lu, Tian " <sobereva+/-sina.com>
 > Subject: CCL:G: How to consider charge on particular atom -lithium
 > Date: 2014-02-11 17:12
 >
 >
 >
 > Sent to CCL by: Susi Lehtola [susi.lehtola-.-alumni.helsinki.fi]
 > On Mon, 10 Feb 2014 18:37:44 -0500
 > "Jim Kress ccl_nospam_._kressworks.com"
 <owner-chemistry%a%ccl.net> wrote:
 > > Sent to CCL by: "Jim Kress" [ccl_nospam,kressworks.com]
 > > AIM and NBO charges would be the best choice. Mulliken and Lowdin are
 far too basis set dependent.
 > NBO charges are explicitly dependent on the basis set, like Mulliken
 > and Lwdin.
 > AIM charges are not, but then again according to them e.g. H2O and HCN
 > are ionic...
 > Probably the best scheme is something like the recently proposed
 > iterative Hirshfeld schemes, but I'm not aware of any program that
 > implements these.
 > Another possibility are electrostatic potential charges, which are
 > available in e.g. Gaussian.
 > --
 > ---------------------------------------------------------------
 > Mr. Susi Lehtola, PhD Research Associate
 > susi.lehtola%a%alumni.helsinki.fi Department of Applied Physics
 > http://www.helsinki.fi/~jzlehtol Aalto University>
 Finland
 > ---------------------------------------------------------------
 > Susi Lehtola, FT Tutkijatohtori
 > susi.lehtola%a%alumni.helsinki.fi Fysiikan laitos
 > http://www.helsinki.fi/~jzlehtol Aalto-yliopisto>
 --
    Brian Salter-Duke (Brian Duke)   Brian.Salter-Duke|monash.edu
                     Adjunct Associate Professor
             Monash Institute of Pharmaceutical Sciences
       Monash University Parkville Campus, VIC 3052, Australiahttp://www.ccl.net/cgi-bin/ccl/send_ccl_messagehttp-:-//www.ccl.net/chemistry/sub_unsub.shtmlhttp-:-//www.ccl.net/spammers.txt===========End
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