1997 Sept 22
 On Sept 17 I asked:
 > Hello,  Does anyone know who first used the LCAO method of approximating
 > molecular orbitals, and in what year?  It must have been in 1926, 1927,
 > or 1928.  I suspect that Lennard-Jones was not actually the first.
 >   Thanks
 >    E. Lewars
 > =======
 These are the replies I got.  It seems that Heitler and London's 1927 calcs
 on H2 were in the spirit of VB rather than MO calculations (Andrew Pudzianowski,
 #4). Thus the priority evidently goes to Finkelstein and Horowitz (1928) and
 Mulliken (1926 and subsequent years), which latter systematized and explored
 the LCAO approach thoroughly. Hund (I think he is still alive, aged 101*) also
 used the method (1928).  The terms _orbital_ and _LCAO_ are evidently due to
 Mulliken.  Roothans contribution (1951) was to propose applying the LCAO
 method to the Hartree-Fock equations, thus transforming them from a problem
 in differential equations, which no one understands, to a problem in linear
 algebra, which everyone understands.
 * W. Kutzelnigg, "Fredrich Hund and Chemistry" Ang Chem Int Ed Engl,
   35 (1996) 573-586).
   Thanks very much to all who offered me information on this matter.
    E. Lewars
 I believe it was Heitler and London's calculations on the hydrogen molecule
 where they made use of hydrogen atomic orbitals (Z. Phys. 44, 455, 1927). The
 technique was formalized by Mulliken in 1935 and introduced the terminology
 LCAO (JCP 3, 375, 1935).
 best regards,
 Kirk A. Peterson
 Assistant Professor              Affiliate Senior Research Scientist
 Department of Chemistry     &    Theory, Modeling, and Simulation
 Washington State University      Environmental Molecular Sciences Laboratory
 Richland, WA                     Pacific Northwest National Laboratory
 Office: (509) 375-6350, (509) 372-7282
 Fax:    (509) 375-6631
                      kirk.peterson -x- at -x-
 >From boufer -x- at -x- Thu Sep 18 06:49:10 EDT 1997
 Date: Thu, 18 Sep 1997 06:49:06 -0400 (EDT)
 >From: Ahmed Bouferguene <boufer -x- at -x->
 X-Sender: boufer -x- at -x- cennas
 To: "E. Lewars" <elewars -x- at -x->
 I think the first treatment was to Heitler and London (Hydrogen molecule)
 and it was in 1927 (Z. Physik 44, 455 (1927)).
  Ahmed Bouferguene
 >From sichelj -x- at -x- Thu Sep 18 08:48:17 EDT 1997
 Date: Thu, 18 Sep 1997 09:49:59 -0300 (ADT)
 >From: "J. Sichel" <sichelj -x- at -x->
 To: "E. Lewars" <elewars -x- at -x->
 Cc: chemistry -x- at -x-
 According to Levine's Quantum Chemistry (4th edn p.357):
   The [LCAO] trial function [for H2] was first used by Finkelstein and
 Horowitz in 1928. Unfortunately he does not give a journal reference.
 John Sichel
 Universit=E9 de Moncton, NB, Canada
 >From PUDZIANA -x- at -x- Thu Sep 18 10:10:22 EDT 1997
 >From: PUDZIANA -x- at -x-
 Date: Thu, 18 Sep 1997 10:11:55 -0500 (EST)
 Subject: LCAO origins
 To: elewars -x- at -x-
 Errol -
    As far as I know, Robert Mulliken originated both the orbital
 terminology (i.e., referring to functions as orbitals) and the
 term LCAO itself, as well as the general strategy of using LCAO
 to construct approximations to molecular wave functions. The
 pertinent references here would be Phys. Rev. 41, 49 (1932) and
 J. Chem. Phys. 3, 375 (1935).
    Others had used linear combinations involving AO's, e.g.,
 Heitler and London [Z. Phys. 44, 455 (1927)] and Sugiura
 [Z. Phys. 45, 484 (1927)], but this was in the context of
 what we now call VB calculations on the H2 molecule and
 the atomic functions entered the treatment as products, i.e.,
 not in linear sums of individual functions centered on one atom
 each. Thus, I think Mulliken has the real priority here.
                  Andrew Pudzianowski
 Andrew T. Pudzianowski,Ph.D.
 Bristol-Myers Squibb PRI
 Box 4000                  *   "I used to shave with Ockham's Razor,
 Princeton NJ 08543-4000   *    but I kept on getting Dedekind cuts."
 (609) 252-4248            *
 (609) 252-6030: fax       *                ATP (1997)
 pudziana -x- at -x-          *
 >From adler -x- at -x- Thu Sep 18 11:26:33 EDT 1997
 >From: "Thomas A Adler" <adler -x- at -x->
 Organization: Albany Research Center, DOE
 To: "E. Lewars" <elewars -x- at -x->
 Date: Thu, 18 Sep 1997 08:25:34 PST
 Priority: normal
 Pauling and Wilson in their book refer to the following papers about
 the method of molecular orbitals:
 F. Hund, Z. f. Phys. 51, 759 (1928)
 R. S. Mulliken, Phys. Rev. 32. 186, 761 (1928).
 Thomas A. Adler
 Albany Research Center, Department of Energy
 1450 Queen Avenue, SW
 Albany OR 97321-2198
 E-mail:  adler -x- at -x-
 (541) 967-5853
 >From martine -x- at -x- pleiades Thu Sep 18 11:36:23 EDT 1997
 Date: Thu, 18 Sep 1997 08:35:02 -0700
 >From: Eric Martin <martine -x- at -x->
 To: elewars -x- at -x-
 Subject: LCAO
 Hello E.
 I believe it was Roothan, but I don't have any reference books here at
 home.  However, looking up his name in a QM book is likely to confirm
 (or contradict) it.
 Cheers, Eric
 Eric Martin
 martine -x- at -x-
 4560 Horton St., Emeryville, CA 94608
 (510)923-3306,  FAX (510)923-3360
 >From ryszard -x- at -x- Fri Sep 19 21:25:59 EDT 1997
 Date: Thu, 18 Sep 1997 05:57:28 -0700
 >From: Ryszard Czerminski <ryszard -x- at -x->
 To: "E. Lewars" <elewars -x- at -x->
 As far as I remember it was W. Heitler doing calculations
 for H2 or H2+ around the time you mentioned...
 Ryszard Czerminski         phone : (617)354-3124 x 13
 Moldyn, Inc.               fax   : (617)491-4522
 955 Massachusetts Avenue   e-mail: ryszard -x- at -x-
 Cambridge MA, 02139-3180   or      ryszard -x- at -x-