From owner-chemistry@ccl.net Sat Feb 21 12:40:01 2015 From: "Caio Firme firme.caio[*]gmail.com" To: CCL Subject: CCL: QTAIM or else Message-Id: <-51057-150221120335-13250-GTN2CVnCUo9SOLpQ3tthlw],[server.ccl.net> X-Original-From: Caio Firme Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Date: Sat, 21 Feb 2015 14:03:29 -0300 MIME-Version: 1.0 Sent to CCL by: Caio Firme [firme.caio^^^gmail.com] Theoreticians should be aware of limitations of any quantum chemistry theoretical model. For example, when using MO wave functions for treating chemical bonds one should be aware that the chosen set of MOs is not univocal since one is dealing with Slater determinants. Moreover, one should be aware that MO wave functions do not have permutation symmetry (http://arxiv.org/pdf/quant-ph/0301020v1.pdf). One should be aware that a wave function must be a product of spatial and spin functions independently since Schroedinger solution does not include spin quantum number. Only VB wave functions are univocal and independent spatial-spin product and they have permutation symmetry (http://jbcs.sbq.org.br/imagebank/pdf/v19n2a07.pdf). Then, to be strictly rigorous nobody should use MO orbitals to describe any chemical bond. But that is quite usual. Why? For historical reasons. But if works, that´s ok. In one of my works I used MO orbitals and they explained satisfactorily the multicenter bonding. In another work I used NBO bond order which correlated very well with DI bond order (from QTAIM). Then, that´s ok in my opinion. However, when telling (between the lines) that one cannot use QTAIM for intra/intermolecular interactions and/or chemical bonding (or better, bonded interactions), first of all, one should recall the paper (J. Phys. Chem. A2006,110,6365-6371) in which it was listed several examples of experimental evidences that were predicted by QTAIM. Moreover, one should observe whether the vibrational mode are IR active or not. For example, for alkanes, there is no C-C IR absorption which does not mean there is no C-C bond in alkanes. From our work of alkane complexes, where we showed the existence of H-H bonds (J. Phys. Chem. A2014, 118, 1730−1740), if one takes the ethane-ethane complex from wB97XD/6-311++G(d,p) level of theory, one will see that there are 42 vibrational modes in which there are 14 vibrational modes whose IR intensities are -2 order of magnitude or zero (including C-C stretching mode); 5 vibrational modes are -1 order of magnitude. Certainly, one may assume that these 19 vibrational modes are IR inactive. Out of them there are 4 vibrational modes (whose frequencies varied from 98 to 160 cm-1 and their IR intensities varied from 0.0013 to 0.0171) which can be related to H-H bonds but they are practically IR inactive modes. Eventually, in a recent experimental and theoretical work on bioactive clerodane trans-dehydrocrotonin (http://jbcs.sbq.org.br/imagebank/pdf/v25n4a03.pdf) we showed that there is an excellent correlation between spin-spin coupling constants and hydrogen-hydrogen QTAIM delocalization indexes (including H-H bonds). Then, does not QTAIM predict experimental? Moreover, in my most recent papers, I have been working with two or more models for bonded interactions than only one "preferable theory". I have been using QTAIM, ELF and GVB in my recent works. But I was convinced by Cukrowski and collaborators' work (http://pubs.acs.org/doi/pdf/10.1021/jp410744x) that is also important to incorporate NCI and IQA in my works. In this work, Cukrowski et al. used QTAIM, NCI, IQA and ETS-NOCV approaches to study Zn(II) complexes whose results were convergent including the existence of stabilizing H-H bond. Nonetheless, It does not mean we must use (or only use) one´s preferable model. One´s preferable model when is not used in a work should not be the main reason for the refusal of quality of this work. One should ask whether the wave function was appropriate; whether the used models were appropriate; whether the objectives were appropriately reached. That´s my opinion. I hope this point of view can help you in your future works, dear Lukman. Caio Federal University of Rio Grande do Norte Natal, Brazil. 2015-02-20 16:07 GMT-03:00 Stefan Grimme grimme..thch.uni-bonn.de : > > > Sent to CCL by: "Stefan Grimme" [grimme- -thch.uni-bonn.de] > > >I do not at all agree with the statement of Prof Grimme saying that > >"I don't think that QTAIM can give you a reasonable answer because its >predictions are in serious disagreement with experimental data for a >related case," > > >This paper has been rebutted by Bader and also by myself in > >The QTAIM Perspective of Chemical Bonding , P.L.A. Popelier in > >The Nature of the Chemical Bond Revisited, Chapter 8, pp 271-308 (pp 1-38), >Eds. G. Frenking and S. Shaik, Wiley-VCH, 2014. > > >For your convenience let me quote a relevant passage from this Chapter: > > >"Moreover, it should be emphasized that the German authors invoked the > >architecture of the MM3 force field in order to separate molecular potential energy into chemically meaningful parts." > > A force-field was merely used for further analysis but the main point of the > paper, the EXPERIMENTALLY OBSERVED tiny splitting between the symmetric and anti-symmetric stretch C-D vibrations in dideutero-phenanthrene is not > affected or related to its use. The strong interpretation of the QTAIM that energy local lowerings ("bonding") have a chemical meaning is falsified by the experiment in the original paper. According to to QTAIM one would expect a large splitting (of +/- sign depending if its repulsive or attractive) but practically nothing (about 10 cm^-1) is seen. I don't seen any reasonable rebuttal to this fact. As mentioned already in the original work, an energy lowering of 7-8 kcal/mol for this D...D interaction as predicted by QTAIM should lead to splittings on the order of hundreds of cm^-1. > > > Cheers! > Stefan> > From owner-chemistry@ccl.net Sat Feb 21 15:28:01 2015 From: "Robert Molt r.molt.chemical.physics a gmail.com" To: CCL Subject: CCL: QTAIM or else Message-Id: <-51058-150221142734-32031-c73jJOZr/4TplK6BT+iflQ^^^server.ccl.net> X-Original-From: Robert Molt Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=utf-8; format=flowed Date: Sat, 21 Feb 2015 14:27:25 -0500 MIME-Version: 1.0 Sent to CCL by: Robert Molt [r.molt.chemical.physics : gmail.com] "...MO wavefunctions do not have permutation symmetry." That's utter nonsense. HF, CI, and CC wavefunctions all have correct permutational symmetry, and they are all molecular orbital wavefunctions. "One should be aware that a wave function must be a product of spatial and spin functions independently...Only VB wave functions are univocal and independent spatial-spin product and they have permutation symmetry" Completely false. Look at the equations for HF and then correlated wavefunctions, one writes a product of spatial and spin functions independently. Szabo and Ostlund goes through all of this in detail (the 101 book in quantum chemistry). On 2/21/15 12:03 PM, Caio Firme firme.caio[*]gmail.com wrote: > Sent to CCL by: Caio Firme [firme.caio^^^gmail.com] > Theoreticians should be aware of limitations of any quantum chemistry > theoretical model. For example, when using MO wave functions for > treating chemical bonds one should be aware that the chosen set of MOs > is not univocal since one is dealing with Slater determinants. > Moreover, one should be aware that MO wave functions do not have > permutation symmetry (http://arxiv.org/pdf/quant-ph/0301020v1.pdf). > One should be aware that a wave function must be a product of spatial > and spin functions independently since Schroedinger solution does not > include spin quantum number. Only VB wave functions are univocal and > independent spatial-spin product and they have permutation symmetry > (http://jbcs.sbq.org.br/imagebank/pdf/v19n2a07.pdf). Then, to be > strictly rigorous nobody should use MO orbitals to describe any > chemical bond. But that is quite usual. Why? For historical reasons. > But if works, that´s ok. In one of my works I used MO orbitals and > they explained satisfactorily the multicenter bonding. In another work > I used NBO bond order which correlated very well with DI bond order > (from QTAIM). Then, that´s ok in my opinion. > > However, when telling (between the lines) that one cannot use QTAIM > for intra/intermolecular interactions and/or chemical bonding (or > better, bonded interactions), first of all, one should recall the > paper (J. Phys. Chem. A2006,110,6365-6371) in which it was listed > several examples of experimental evidences that were predicted by > QTAIM. Moreover, one should observe whether the vibrational mode are > IR active or not. For example, for alkanes, there is no C-C IR > absorption which does not mean there is no C-C bond in alkanes. From > our work of alkane complexes, where we showed the existence of H-H > bonds (J. Phys. Chem. A2014, 118, 1730−1740), if one takes the > ethane-ethane complex from wB97XD/6-311++G(d,p) level of theory, one > will see that there are 42 vibrational modes in which there are 14 > vibrational modes whose IR intensities are -2 order of magnitude or > zero (including C-C stretching mode); 5 vibrational modes are -1 order > of magnitude. Certainly, one may assume that these 19 vibrational > modes are IR inactive. Out of them there are 4 vibrational modes > (whose frequencies varied from 98 to 160 cm-1 and their IR intensities > varied from 0.0013 to 0.0171) which can be related to H-H bonds but > they are practically IR inactive modes. > > Eventually, in a recent experimental and theoretical work on bioactive > clerodane trans-dehydrocrotonin > (http://jbcs.sbq.org.br/imagebank/pdf/v25n4a03.pdf) we showed that > there is an excellent correlation between spin-spin coupling constants > and hydrogen-hydrogen QTAIM delocalization indexes (including H-H > bonds). Then, does not QTAIM predict experimental? > > Moreover, in my most recent papers, I have been working with two or > more models for bonded interactions than only one "preferable theory". > I have been using QTAIM, ELF and GVB in my recent works. But I was > convinced by Cukrowski and collaborators' work > (http://pubs.acs.org/doi/pdf/10.1021/jp410744x) that is also important > to incorporate NCI and IQA in my works. In this work, Cukrowski et al. > used QTAIM, NCI, IQA and ETS-NOCV approaches to study Zn(II) complexes > whose results were convergent including the existence of stabilizing > H-H bond. Nonetheless, It does not mean we must use (or only use) > one´s preferable model. One´s preferable model when is not used in a > work should not be the main reason for the refusal of quality of this > work. One should ask whether the wave function was appropriate; > whether the used models were appropriate; whether the objectives were > appropriately reached. That´s my opinion. > > I hope this point of view can help you in your future works, dear Lukman. > > Caio > Federal University of Rio Grande do Norte > Natal, Brazil. > > > 2015-02-20 16:07 GMT-03:00 Stefan Grimme grimme..thch.uni-bonn.de > : >> >> Sent to CCL by: "Stefan Grimme" [grimme- -thch.uni-bonn.de] >> >>> I do not at all agree with the statement of Prof Grimme saying that >>> "I don't think that QTAIM can give you a reasonable answer because its >predictions are in serious disagreement with experimental data for a >related case," >>> This paper has been rebutted by Bader and also by myself in >>> The QTAIM Perspective of Chemical Bonding , P.L.A. Popelier in >>> The Nature of the Chemical Bond Revisited, Chapter 8, pp 271-308 (pp 1-38), >Eds. G. Frenking and S. Shaik, Wiley-VCH, 2014. >>> For your convenience let me quote a relevant passage from this Chapter: >>> "Moreover, it should be emphasized that the German authors invoked the >>> architecture of the MM3 force field in order to separate molecular potential energy into chemically meaningful parts." >> A force-field was merely used for further analysis but the main point of the >> paper, the EXPERIMENTALLY OBSERVED tiny splitting between the symmetric and anti-symmetric stretch C-D vibrations in dideutero-phenanthrene is not >> affected or related to its use. The strong interpretation of the QTAIM that energy local lowerings ("bonding") have a chemical meaning is falsified by the experiment in the original paper. According to to QTAIM one would expect a large splitting (of +/- sign depending if its repulsive or attractive) but practically nothing (about 10 cm^-1) is seen. I don't seen any reasonable rebuttal to this fact. As mentioned already in the original work, an energy lowering of 7-8 kcal/mol for this D...D interaction as predicted by QTAIM should lead to splittings on the order of hundreds of cm^-1. >> >> >> Cheers! >> Stefan> > -- Dr. Robert Molt Jr. r.molt.chemical.physics|a|gmail.com Nigel Richards Research Group Department of Chemistry & Chemical Biology Indiana University-Purdue University Indianapolis LD 326 402 N. Blackford St. Indianapolis, IN 46202 From owner-chemistry@ccl.net Sat Feb 21 18:22:01 2015 From: "Caio Firme firme.caio,,gmail.com" To: CCL Subject: CCL: QTAIM or else Message-Id: <-51059-150221180748-12267-gKt+0WZk73VhCp15rPCSNw%%server.ccl.net> X-Original-From: Caio Firme Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Date: Sat, 21 Feb 2015 20:07:36 -0300 MIME-Version: 1.0 Sent to CCL by: Caio Firme [firme.caio#%#gmail.com] Please read carefully the cited paper in the first paragraph of the previous text (Nascimento´s work). It is not said that Slater determinants (MO wave function) are not antisymmetrical under permutation of two electrons.It is not said that does not have spatial and spin product in MO wave function. However, Slater determinants are simple orthogonal spin-orbitais singly antisymmetrized which means they do not have permutation symmetry and they do not have independent spatial and spin functions. Citing McWeeny´s Methods of Molecular Quantum Mechanics, 2nd ed, chapter 4 (spin and permutation symmetry) one reads: "It was shown that for a two-electron system the antisymmetry principle could also be satisfied by writing the wavefunction as a product of individually symmetric and antisymmetric factors - one for spatial variables and the other for spin variables." "The fundamental question, even for exact solutions of the Schroedinger equation, will therefore be how to combine space and spin functions in order to describe a state of given energy and spin, which at the same time satisfies the Pauli Principle; the space-spin function, no matter how it be constructed, must be antisymmetric for any permutation applied simultaneously to space and spin variables." "In last section it was noted that a full set of linearly independent eigenfunctions of spin operators S2 adn Sz provides a basis for a representation of the group (SN) of N! permutation operators applied to the spin variables s1, s2,...,sN. (...) Exact parallel considerations apply to the spatial wavefunctions, which are eigenfunctions of a Hamiltonian operator that is invariant under all permutations of spatial variables, and a g-fold degenerate set of (spinless) wave functions should likewise carry an irrep of SN." It is recommended to read this chapter thourougly. Then wave function with permutation symmetry means that "both the spatial and spin parts must independently exhibit permutation symmetry, i.e., must transform like the irreducible representations of the symmetric (SN) group", citing Nascimento´s work (JBCS, 2008, 19, 245). Caio Federal University of Rio Grande do Norte Natal, Brazil. 2015-02-21 16:27 GMT-03:00 Robert Molt r.molt.chemical.physics a gmail.com : > > Sent to CCL by: Robert Molt [r.molt.chemical.physics : gmail.com] > "...MO wavefunctions do not have permutation symmetry." > > That's utter nonsense. HF, CI, and CC wavefunctions all have correct > permutational symmetry, and they are all molecular orbital wavefunctions. > > "One should be aware that a wave function must be a product of spatial and > spin functions independently...Only VB wave functions are univocal and > independent spatial-spin product and they have permutation symmetry" > > Completely false. Look at the equations for HF and then correlated > wavefunctions, one writes a product of spatial and spin functions > independently. > > Szabo and Ostlund goes through all of this in detail (the 101 book in > quantum chemistry). > > > On 2/21/15 12:03 PM, Caio Firme firme.caio[*]gmail.com wrote: >> >> Sent to CCL by: Caio Firme [firme.caio^^^gmail.com] >> Theoreticians should be aware of limitations of any quantum chemistry >> theoretical model. For example, when using MO wave functions for >> treating chemical bonds one should be aware that the chosen set of MOs >> is not univocal since one is dealing with Slater determinants. >> Moreover, one should be aware that MO wave functions do not have >> permutation symmetry (http://arxiv.org/pdf/quant-ph/0301020v1.pdf). >> One should be aware that a wave function must be a product of spatial >> and spin functions independently since Schroedinger solution does not >> include spin quantum number. Only VB wave functions are univocal and >> independent spatial-spin product and they have permutation symmetry >> (http://jbcs.sbq.org.br/imagebank/pdf/v19n2a07.pdf). Then, to be >> strictly rigorous nobody should use MO orbitals to describe any >> chemical bond. But that is quite usual. Why? For historical reasons. >> But if works, that´s ok. In one of my works I used MO orbitals and >> they explained satisfactorily the multicenter bonding. In another work >> I used NBO bond order which correlated very well with DI bond order >> (from QTAIM). Then, that´s ok in my opinion. >> >> However, when telling (between the lines) that one cannot use QTAIM >> for intra/intermolecular interactions and/or chemical bonding (or >> better, bonded interactions), first of all, one should recall the >> paper (J. Phys. Chem. A2006,110,6365-6371) in which it was listed >> several examples of experimental evidences that were predicted by >> QTAIM. Moreover, one should observe whether the vibrational mode are >> IR active or not. For example, for alkanes, there is no C-C IR >> absorption which does not mean there is no C-C bond in alkanes. From >> our work of alkane complexes, where we showed the existence of H-H >> bonds (J. Phys. Chem. A2014, 118, 1730−1740), if one takes the >> ethane-ethane complex from wB97XD/6-311++G(d,p) level of theory, one >> will see that there are 42 vibrational modes in which there are 14 >> vibrational modes whose IR intensities are -2 order of magnitude or >> zero (including C-C stretching mode); 5 vibrational modes are -1 order >> of magnitude. Certainly, one may assume that these 19 vibrational >> modes are IR inactive. Out of them there are 4 vibrational modes >> (whose frequencies varied from 98 to 160 cm-1 and their IR intensities >> varied from 0.0013 to 0.0171) which can be related to H-H bonds but >> they are practically IR inactive modes. >> >> Eventually, in a recent experimental and theoretical work on bioactive >> clerodane trans-dehydrocrotonin >> (http://jbcs.sbq.org.br/imagebank/pdf/v25n4a03.pdf) we showed that >> there is an excellent correlation between spin-spin coupling constants >> and hydrogen-hydrogen QTAIM delocalization indexes (including H-H >> bonds). Then, does not QTAIM predict experimental? >> >> Moreover, in my most recent papers, I have been working with two or >> more models for bonded interactions than only one "preferable theory". >> I have been using QTAIM, ELF and GVB in my recent works. But I was >> convinced by Cukrowski and collaborators' work >> (http://pubs.acs.org/doi/pdf/10.1021/jp410744x) that is also important >> to incorporate NCI and IQA in my works. In this work, Cukrowski et al. >> used QTAIM, NCI, IQA and ETS-NOCV approaches to study Zn(II) complexes >> whose results were convergent including the existence of stabilizing >> H-H bond. Nonetheless, It does not mean we must use (or only use) >> one´s preferable model. One´s preferable model when is not used in a >> work should not be the main reason for the refusal of quality of this >> work. One should ask whether the wave function was appropriate; >> whether the used models were appropriate; whether the objectives were >> appropriately reached. That´s my opinion. >> >> I hope this point of view can help you in your future works, dear Lukman. >> >> Caio >> Federal University of Rio Grande do Norte >> Natal, Brazil. >> >> >> 2015-02-20 16:07 GMT-03:00 Stefan Grimme grimme..thch.uni-bonn.de >> : >>> >>> >>> Sent to CCL by: "Stefan Grimme" [grimme- -thch.uni-bonn.de] >>> >>>> I do not at all agree with the statement of Prof Grimme saying that >>>> "I don't think that QTAIM can give you a reasonable answer because its >>>> >predictions are in serious disagreement with experimental data for a >>>> >related case," >>>> This paper has been rebutted by Bader and also by myself in >>>> The QTAIM Perspective of Chemical Bonding , P.L.A. Popelier in >>>> The Nature of the Chemical Bond Revisited, Chapter 8, pp 271-308 (pp >>>> 1-38), >Eds. G. Frenking and S. Shaik, Wiley-VCH, 2014. >>>> For your convenience let me quote a relevant passage from this Chapter: >>>> "Moreover, it should be emphasized that the German authors invoked the >>>> architecture of the MM3 force field in order to separate molecular >>>> potential energy into chemically meaningful parts." >>> >>> A force-field was merely used for further analysis but the main point of >>> the >>> paper, the EXPERIMENTALLY OBSERVED tiny splitting between the symmetric >>> and anti-symmetric stretch C-D vibrations in dideutero-phenanthrene is not >>> affected or related to its use. The strong interpretation of the QTAIM >>> that energy local lowerings ("bonding") have a chemical meaning is falsified >>> by the experiment in the original paper. According to to QTAIM one would >>> expect a large splitting (of +/- sign depending if its repulsive or >>> attractive) but practically nothing (about 10 cm^-1) is seen. I don't seen >>> any reasonable rebuttal to this fact. As mentioned already in the original >>> work, an energy lowering of 7-8 kcal/mol for this D...D interaction as >>> predicted by QTAIM should lead to splittings on the order of hundreds of >>> cm^-1. >>> >>> >>> Cheers! >>> Stefan> >> >> > > -- > Dr. Robert Molt Jr. > r.molt.chemical.physics[-]gmail.com > Nigel Richards Research Group > Department of Chemistry & Chemical Biology > Indiana University-Purdue University Indianapolis > LD 326 > 402 N. Blackford St. > Indianapolis, IN 46202http://www.ccl.net/chemistry/sub_unsub.shtmlConferences: > http://server.ccl.net/chemistry/announcements/conferences/> >