SLATER ORBITALS, EHM ON HHE+, SUMMARY



 1997 Nov 11
 To: chemistry { *at * } www.ccl.net
 >From: E. Lewars
 Re: Answers to my Q about Slater orbitals--summary
 Thanks very much to all who responded to my two questions about Slater orbitals.
 I now provide a summary of the answers.
 #1    wallenborn { *at * } phys.chem.ethz.ch Mon Nov  3 04:31   93/3072
 CCL:G:OVERLAP INTEGRAL AN
 #2    aldert { *at * } chemde4.leidenuniv.nl Mon Nov  3 04:48   44/1863  Re:
 CCL:G:OVERLAP INTEGR
 #3    FREDVC { *at * } ESALP1.EMAIL.DUPONT.COM Mon Nov  3 09:31  111/5012  Re:
 CCL:G:OVERLAP INTEGRA
 #4    smithja { *at * } ucarb.com  Mon Nov  3 09:41  111/4169  RE: G:OVERLAP
 INTEGRAL AN
 #5    herbert.homeier { *at * } chemie.uni-regensburg.de
 #6    ritschel { *at * } tc1.chem.uni-potsdam.de
 #7    satyam { *at * } indigo2.chem.pitt.edu
 #8    rene { *at * } mountain.chem.yorku.ca
 #9    chburger { *at * } aci.unizh.ch
 #10   davide { *at * } stinch10.csmtbo.mi.cnr.it
 -------------------
 #1
 >From wall { *at * } phys.chem.ethz.ch Mon Nov  3 04:31:11 EST 1997
 Date: Mon, 3 Nov 1997 10:31:01 +0100 (CET)
 >From: Ernst-Udo Wallenborn <wallenborn { *at * } phys.chem.ethz.ch>
 To: "E. Lewars" <elewars { *at * } alchemy.chem.utoronto.ca>
 Subject: CCL:G:OVERLAP INTEGRAL AND SLATER FUNNC
 E. Lewars writes:
 [snip]
 >that Mulliken et al published a long paper (J Chem Phys, 17 (1949)
 1248-1267))
 >with recipes for calculating overlap integrals
 you might also want to read Roothaan's article in
 J. Chem. Phys. _19_ (12) 1445 (1951)
 >(1)  In the molecule H-He+ (yes, protonated helium) if the H nucleus has
 >     Cartesians H1(x_1, y_1, z_1) and the He nucleus He2(x_2, y_2, z_2),
 >     where the coordinates are in Angstroms (_not_ atomic units or Bohrs)
 >
 >     and if we write
 >
 >     for H:  phi_1 = a_1 exp{b_1[(x-x_1)^2 + (y-y_1)^2 + (z-z_1)^2]^1/2}
 > and for He: phi_2 = a_2 exp{b_2[(x-x_2)^2 + (y-y_2)^2 + (z-z_2)^2]^1/2}
 >
 >      (usually a is expressed in terms of zeta and pi, b = -zeta, and
 >      the variable is a radius vector r)
 >   QUESTION:  what are a_1 and b_1, as numbers, not Greek letters?
 b_1 is arbitrarily chosen (well, not completely arbitrarily,
 but the rules they're chosen in accordance with are prescriptions
 rather than rules). For Hydrogen one usually has b_1=1.3, for
 Carbon b_1=1.625 and so on. a_1 then is the normalisation factor,
 given for 1s orbitals as a_1=Sqrt[b_1^3/Pi] (ok, on Greek letter left).
 >(2)  If (x_1, y_1, z_1) = (0, 0, 0) and (x_2, y_2, z_2) = (0, 0, 0.800),
 >     (0.800 Angstroms) what is S_12 (as a number, e.g 0.4273 or whatever)?
 If i take b_1=b_2=1.3 then S_12 is 0.595868. But why did you
 want to know this number?
 >(3)  For (x_1, y_1, z_1) = (0, 0, 0) and (x_2, y_2, z_2) = (0, 0, d),
 >     is there a simple function S_12 = f(d) ? (for H, He?  for any two
 >     1s orbitals)?  Of course f will depend parametrically on the a's and
 b's.
 For all 1s orbitals this is not too complicated,
 S_12 = -(1-k)*[(2(1+k)+ra)*exp(-ra)+(2(1-k)+rb)*exp(-rb)]*(Sqrt[(1-t^2)/(r*t)]
 with
 t = (b_1-b_2)/(b_1+b_2)
 ra = b_1*R
 rb = b_2*R
 r  = 0.5*(b_1+b_2)*R
 R = [(x-x_1)^2 + (y-y_1)^2 + (z-z_1)^2]^1/2
 k = 0.5*(t+1/t) if t != 0;
 but you'll find this in the Roothaan article i cited above
 (the formula was derived by him, if i'm not mistaken, of course
 all typos are mine.)
 ============
 #2
 >From aldert { *at * } chemde4.leidenuniv.nl Mon Nov  3 04:48:24 EST 1997
 Date: Mon, 3 Nov 97 10:50:09 +0100
 >From: aldert { *at * } chemde4.leidenuniv.nl (Aldert Westra Hoekzema)
 To: "E. Lewars" <elewars { *at * } alchemy.chem.utoronto.ca>
 Subject: Re:  CCL:G:OVERLAP INTEGRAL AND SLATER FUNNC
 Hi,
 Analytic expressions for all kinds of two-center integrals for
 Slater orbitals can be found in:
 C.C.J. Roothaan, J. Chem. Phys., 19(12), 1445-58 (1951).
 "A Study of Two-Center Integrals Useful in Calculations on
 Molecular Structure. I"
 The expresion for overlap of 2 Slater 1s orbitals with different
 screening constants and the function you are looking for, can be
 found under formula 25.
 As to the screening constants (your b), for H it is simply 1, for
 He I am not aware of a more recent value then 1.6875 taken from:
 E. Clementi & D.L. Raimondi, J. Chem. Phys. 38(11), 2686-9 (1963).
 line 1 [h for help]
 Hope this helps,  Aldert
 -------------------------------------------
 A.J.A. Westra Hoekzema
 Conformational Analysis (Organic Chemistry)
 Leiden Institute of Chemistry,
 Gorlaeus Laboraties, Leiden University
 P.O. Box 9502, 2300 RA Leiden
 The Netherlands
 Phone : +31 715274505
 Fax   : +31 715274488
 E-mail: aldert { *at * } chemde4.LeidenUniv.nl
 -------------------------------------------
  ==============
 #3
 >From FREDVC { *at * } ESALP1.EMAIL.DUPONT.COM Mon Nov  3 09:31:11 EST 1997
 >From: FREDVC { *at * } ESALP1.EMAIL.DUPONT.COM
 Date: Mon, 03 Nov 1997 09:21:06 -0500 (EST)
 Subject: Re: CCL:G:OVERLAP INTEGRAL AND SLATER FUNNC
 To: elewars { *at * } alchemy.chem.utoronto.ca
 The a's are normalization constants dependent on the b's; the b's are STO
 orbital exponents within a multiplicative factor, depending on whether
 Angstroms or Bohrs are being used.  Search out "Slater's rules" on how
 to
 generate these exponents.
 >>
 >>    S_12 = the triple integral from 0--> infinity of phi_1.phi_2
 dxdydz
 >>    must = the correct overlap, if the six Cartesian coordinates are in
 >>    Angstroms.  And of course integral of S_11 = S_22 = 1.
 >>
 The "Angstroms" restriction is a conceptual one on your part.  As long
 as
 we are *consistent* in units-usage, the overlap is independent of this.
 >>(2)  If (x_1, y_1, z_1) = (0, 0, 0) and (x_2, y_2, z_2) = (0, 0, 0.800),
 >>     (0.800 Angstroms) what is S_12 (as a number, e.g 0.4273 or
 whatever)?
 >>
 >>(3)  For (x_1, y_1, z_1) = (0, 0, 0) and (x_2, y_2, z_2) = (0, 0, d),
 >>     is there a simple function S_12 = f(d) ? (for H, He?  for any two
 >>     1s orbitals)?  Of course f will depend parametrically on the a's
 and b's.
 You are thinking in the wrong coordinate system.  STO Overlap integrals are
 carried out in confocal elliptical coordinates; see Eyring, Walter &
 Kimball,
 (e.g., EWK),  "Quantum Chemistry", page 367.  This transformation
 makes it
 convenient to express STO overlaps in terms of the A & B auxiliary
 functions;
 see Mulliken's paper, and pages 388-389 of EWK.
 There is lore that is almost lost on the best way(s) to generate the A & B
 functions.  You should be aware of this before proceeding to doing actual
 calculations.
 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
                            FREDERIC A. VAN-CATLEDGE
 Scientific Computing Division         ||   Office: (302) 695-1187 or 529-2076
 Central Research & Development Dept.  ||
 The DuPont Company                    ||      FAX: (302) 695-9658
 P. O. Box 80320                       ||
 Wilmington DE 19880-0320              || Internet: fredvc { *at * }
 esvax.dnet.dupont.com
 --------------------------------------------------------------------------------
 Opinions expressed in this electronic message should ***> NOT <*** be
 taken to
 represent the official position(s) of the DuPont Company.
 *****> ANY OPINIONS EXPRESSED ARE THE PERSONAL VIEWS OF THE AUTHOR ONLY.
 <*****
 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 ============
 #4
 >From smithja { *at * } ucarb.com Mon Nov  3 09:41:40 EST 1997
 >From: "Smith JA (Jack)" <smithja { *at * } ucarb.com>
 To: "'E. Lewars'" <elewars { *at * } alchemy.chem.utoronto.ca>
 Subject: RE: G:OVERLAP INTEGRAL AND SLATER FUNNC
 Date: Mon, 3 Nov 1997 08:40:32 -0600
 X-Priority: 3
 >  There is some info' about overlap integrals and Slater functions that
 > I am
 > finding it hard to dig out of the literature.  I should state at the
 > outset
 > that _I know_:
 >
 > that there are programs for calculating overlap integrals
 >
 Why do you not want to use existing routines?
 > that in most molecular quantum chem Gaussian functions, not Slater
 > functions,
 > are used
 >
 > that Mulliken et al published a long paper (J Chem Phys, 17 (1949)
 > 1248-1267))
 > with recipes for calculating overlap integrals
 >
 > that all kinds of tricks exist for "simplifying" the calculation
 of
 > overlap
 > integrals
 >
 So what didn't you understand or like?
 > ---------
 > OK, but what I want is simply this:
 >
 > (1)  In the molecule H-He+ (yes, protonated helium) if the H nucleus
 > has
 >      Cartesians H1(x_1, y_1, z_1) and the He nucleus He2(x_2, y_2,
 > z_2),
 >      where the coordinates are in Angstroms (_not_ atomic units or
 > Bohrs)
 >
 >      and if we write
 >
 >      for H:  phi_1 = a_1 exp{b_1[(x-x_1)^2 + (y-y_1)^2 +
 > (z-z_1)^2]^1/2}
 >  and for He: phi_2 = a_2 exp{b_2[(x-x_2)^2 + (y-y_2)^2 +
 > (z-z_2)^2]^1/2}
 >
 >       (usually a is expressed in terms of zeta and pi, b = -zeta, and
 >       the variable is a radius vector r)
 >    QUESTION:  what are a_1 and b_1, as numbers, not Greek letters?
 >               what are a_2,and b_2 as  numbers, not Greek letters?
 >               (i.e a_1 = 0.5647 or whatever, etc etc (4 decimals).
 >
 These are just standard normalization constants (in terms of zeta and
 pi, as you stated). You know the values of zeta and pi, so what's the
 problem?
 >     S_12 = the triple integral from 0--> infinity of phi_1.phi_2
 > dxdydz
 >     must = the correct overlap, if the six Cartesian coordinates are
 > in
 >     Angstroms.
 >
 If you do the integral right, the units shouldn't matter.
 > And of course integral of S_11 = S_22 = 1.
 >
  That's the normalization condition that gives the normalization
 constants.
 > (2)  If (x_1, y_1, z_1) = (0, 0, 0) and (x_2, y_2, z_2) = (0, 0,
 > 0.800),
 >      (0.800 Angstroms) what is S_12 (as a number, e.g 0.4273 or
 > whatever)?
 >
 > (3)  For (x_1, y_1, z_1) = (0, 0, 0) and (x_2, y_2, z_2) = (0, 0, d),
 >      is there a simple function S_12 = f(d) ? (for H, He?  for any two
 >      1s orbitals)?  Of course f will depend parametrically on the a's
 > and b's.
 >
 I recommend that you get a copy of Slater's book "Quantum Theory of
 Matter" (2nd Edition, McGraw-Hill, 1968) and look at chapter 20 (the H2+
 problem).  You should be able to solve your HHe+ problem by hand based
 on this alone (and perhaps some of the earlier chapters dealing with
 Slater functions - although Slater doesn't call them that, of course!).
 If you can't find a copy, I'll send you the actual formulas.
 I can't tell whether you're over-complicating a simple problem, or
 over-simplifying a complicated problem.
 - Jack
 P.S.  I also have a complete STO package for all 1-center (1-and
 2-electron) integrals and all 2-center overlap and nuclear
 attraction-type integrals for any arbitrary orientation (with no hard
 limit on quantum numbers).  It's not a stand-alone package, but rather
 part of a larger molecular package that I wrote over 20 years ago, and
 it's in old ANSI-66 Fortran.  (It uses most of the "tricks" with the A
 and B functions involving recursion formulas, etc., that you probably
 read about, and perhaps a few you haven't read about).
 =============
 #5
 >From herbert.homeier { *at * } chemie.uni-regensburg.de Mon Nov  3 11:08:00
 EST 1997
 Date: Mon, 3 Nov 97 17:59:30 +0100
 >From: Herbert Homeier t4720 <herbert.homeier { *at * }
 chemie.uni-regensburg.de>
 To: elewars { *at * } alchemy.chem.utoronto.ca
 Subject: Re: CCL:G:OVERLAP INTEGRAL AND SLATER FUNNC
 Cc: CHEMISTRY { *at * } ccl.net
 Reply-To: herbert.homeier { *at * } na-net.ornl.gov
 Hello,
 > Date: Sun, 2 Nov 1997 16:54:11 -0500 (EST)
 > From: "E. Lewars" <elewars { *at * }
 alchemy.chem.utoronto.ca>
 > Message-Id: <199711022154.QAA26919 { *at * }
 alchemy.chem.utoronto.ca>
 > To: chemistry { *at * } www.ccl.net
 > Subject: CCL:G:OVERLAP INTEGRAL AND SLATER FUNNC
 >
 >
 > There is some info' about overlap integrals and Slater functions that I am
 > finding it hard to dig out of the literature. I should state at the outset
 > that _I know_:
 >
 > that there are programs for calculating overlap integrals
 >
 > that in most molecular quantum chem Gaussian functions, not Slater
 > functions,
 > are used
 >
 > that Mulliken et al published a long paper (J Chem Phys, 17 (1949)
 > 1248-1267))
 > with recipes for calculating overlap integrals
 that contains quite a few errors ....
 >
 > that all kinds of tricks exist for "simplifying" the calculation
 of overlap
 > integrals
 > ---------
 > OK, but what I want is simply this:
 > (1) In the molecule H-He+ (yes, protonated helium) if the H nucleus has
 > Cartesians H1(x_1, y_1, z_1) and the He nucleus He2(x_2, y_2, z_2),
 > where the coordinates are in Angstroms (_not_ atomic units or Bohrs)
 >
 > and if we write
 >
 > for H: phi_1 = a_1 exp{b_1[(x-x_1)^2 + (y-y_1)^2 + (z-z_1)^2]^1/2}
 > and for He: phi_2 = a_2 exp{b_2[(x-x_2)^2 + (y-y_2)^2 + (z-z_2)^2]^1/2}
 The best source of information on such questions is still the
 "classical" paper
 E. Clementi and C. Roetti, At. Data & Nucl. Data Tables 14 (1974) 177
 [maybe in atomic units, though 8^)]
 >
 > (usually a is expressed in terms of zeta and pi, b = -zeta, and
 > the variable is a radius vector r)
 > QUESTION: what are a_1 and b_1, as numbers, not Greek letters?
 > what are a_2,and b_2 as numbers, not Greek letters?
 > (i.e a_1 = 0.5647 or whatever, etc etc (4 decimals).
 >
 > S_12 = the triple integral from 0--> infinity of phi_1.phi_2 dxdydz
 line 48 [h for help]> must = the correct overlap, if the six Cartesian
 coordinates are in
 > Angstroms. And of course integral of S_11 = S_22 = 1.
 >
 > (2) If (x_1, y_1, z_1) = (0, 0, 0) and (x_2, y_2, z_2) = (0, 0, 0.800),
 > (0.800 Angstroms) what is S_12 (as a number, e.g 0.4273 or whatever)?
 >
 > (3) For (x_1, y_1, z_1) = (0, 0, 0) and (x_2, y_2, z_2) = (0, 0, d),
 > is there a simple function S_12 = f(d) ? (for H, He? for any two
 > 1s orbitals)? Of course f will depend parametrically on the a's and b's.
 > ----------
 The answer to your final question is given below, however, in somewhat
 different notation:
 alpha : -b_1
 beta  : -b_2
 R     : d
 my S  : Overlap of exp(-alpha*r_1) and exp(-beta*r_2), ie., for a_1=a_2=1,
         where r_1=sqrt(x**2+y**2+z**2) and
               r_2=sqrt(x**2+y**2+(z-R)**2)
 The result of the fortran program listed below contains also the
 value where a_1 and a_2 are chosen so that the 1s orbitals are
 normalized. See the output.
 There is an WWW interface to this:
 http://www.chemie.uni-regensburg.de/~hoh05008/form-Soverlap.html
 For 1s functions, of course, the result for the overlap integral
 does only depends on a_1,a_2,b_1,b_2 and d, not on the particular
 geometry of the centers (only their distance d matters).
 As regards units:
 If you enter R in Angstroem, and alpha and beta in 1/Angstroem,
 everything should be fine in the case of the overlap integral of
 normalized 1s functions.
 You may be interested also in the following papers:
  { *at * } ARTICLE{HomeierSteinborn92ote,
         author={H. H. H. Homeier and E. O. Steinborn},
         title={On the
 Evaluation of Overlap Integrals with Exponential--type Basis
 Functions},
         journal="Int. J. Quantum Chem.",
         volume=42,
         pages="761--778",
         year="1992"
 }
  { *at * } ARTICLE{HomeierWenigerSteinborn92pft,
         author={H. H. H. Homeier and E. J. Weniger and E. O. Steinborn},
         title={Programs for the Evaluation of Overlap Integrals with
 {$B$} Functions},
         journal="Comput. Phys. Commun.",
         volume=72,
         pages="269--287",
         year="1992"
 The latter describes a fortran program package S_INT for more general orbitals.
 The output generated by the programs given below has been checked against
 the output of this package.
 One should be careful (!), however, with the closed form expression
 coded in the programs below in the case that alpha and beta are not
 equal, but very close, and in the case that R is small but not exactly
 zero. The reason is that in these cases, cancelling singularities turn
 up. For instance, one gets a result somewhat greater than one for the
 normalized functions for alpha=1.000 beta=1.001 R=0.01 and this, of
 course is wrong (overlaps of normalized functions have to be smaller
 than 1.
 The package S_INT generates accurate output even in the case described above.
 Best regards
 Herbert Homeier
 ----------[PROGRAMS AVAILABLE FROM HERBERT HOMEIER]-
 --------------------------------------------------------------
 Priv.-Doz. Dr. Herbert H. H. Homeier
 Institut fuer Physikalische und Theoretische Chemie
 Universitaet Regensburg, D-93040 Regensburg, Germany
 Phone: +49-941-943 4720  FAX: +49-941-943 4719/+49-941-943 2305
 email: herbert.homeier { *at * } na-net.ornl.gov
 WWW: http://www.chemie.uni-regensburg.de/~hoh05008
 ===============
 #6
 >From ritschel { *at * } tc1.chem.uni-potsdam.de Tue Nov  4 07:25:07 EST 1997
 >From: ritschel { *at * } tc1.chem.uni-potsdam.de (Thomas Ritschel)
 Subject: Overlap Integrals over Slater Functions
 To: elewars { *at * } alchemy.chem.utoronto.ca
 Date: Tue, 4 Nov 1997 13:24:35 +0100 (MET)
 Dear Dr. Lewars,
 some months ago I wrote a small C program which computes overlap
 integrals over slater type functions. The program was originally
 written with Turbo C on a PC, but it runs also on an IBM RS/6000
 and therefore it shold be runing at yours too.
 The code is not very fast and sometimes it makes some trouble.
 The calculation is done in elliptical coordinates and with the use
 of auxiliary integrals A and B. The theory about this I found in
 the (german) book "Quantenchemie - Ein Lehrgang. Band 5: Ausgewaehlte
 Mathematische Methoden der Chemie" by H.-J. Glaeske, J. Reinhold and
 P. Volkmer, but I think that there are a lot of english written books
 on this topic too.
 Some words to the use of the program:
 You have to specify the bond distance, e.g. the distance between
 the 2 nuclei. In your CCL mail you wrote that you use cartesian
 coordinates, so you have to calc   r = sqrt(x*x + y*y + z*z).
 The program internally uses atomic units (bohr) - so you have to
 convert your angstrom values to a.u. by dividing them by 0.529177.
 This value is defined as a constant with the name "bohr" in my
 program.
 The function for computing the overlap integral is called in that
 way:
    s = overlap(s1s, 1.24, s1s, 2.0925, sigma, r/bohr);
 The six parameters are:
 s1s    ... use a 1s orbital on first atom
 1.24   ... the slater orbital exponent on first atom (= zeta)
 s1s    ... use a 1s orbital on second atom
 2.0925 ... the slater orbital exponent on second atom (= zeta)
 sigma  ... we have a sigma type of bond
 r/bohr ... bond distance in a.u. (r is in angstrom)
 I've tested it on your H + He(+) and it seems to work well.
 The zeta value's may be different to them you use. For hydrogen
 normally a value of 1.30 is taken for extended huckel calculations.
 Be sure that you never call the overlap function with r = 0.0
 otherwise you'll get some waste data. If you want to calc S12(0.0)
 then take r = 0.0001 or so.
 That's all to say about the program.
 I hope I could help you. Fell free to ask me if you have some trouble
 with the code.
 Thomas.
 ----------------------------------------
             Thomas Ritschel
          Universitaet Potsdam
       Institut fuer Physikalische
         und Theoretische Chemie
     ritschel { *at * } tc1.chem.uni-potsdam.de
 ----------------------------------1997--
                      [PROGRAM AVAILABLE FROM THOMAS RITSCHEL]
 ==========
 #7
 >From:  IN%"satyam { *at * } indigo2.chem.pitt.edu"
 "satyam"
 To:     IN%"elewars { *at * } alchemy.chem.utoronto.ca"  "E.
 Lewars"
 CC:     IN%"chemistry { *at * } www.ccl.net"
 Subj:   CCL:SLATER ORBITALS-THANKS AND A REQUEST
 A quick calculation using HYPERCHEM5.01  version
 gives the following result :
 H-He+       R=0.8 Ang          R=0.774 Ang
 HOMO        -25.8147  eV       -25.8767 eV
 LUMO        - 2.3698  eV       - 1.2903 eV
 The results with Weighted Diffusion option gives the following
 HOMO       -26.1629  eV       -26.2390
 LUMO       - 0.9855  eV       + 0.2135
 Satyam
 On Fri, 7 Nov 1997, E. Lewars wrote:
 > Friday 1997 Nov 7
 >
 >   Thanks to all those who responded to my question about Slater orbitals; I
 wi
 ll
 > post a summary and an explanation in a couple days.
 >
 >   One more request: if anyone has an extended Hueckel program and a couple
 > minutes to spare, could he/she tell me what eigenvalues and eigenvectors it
 > gives for H-He+ at an internuclear distance of 0.800 A (1.512 a.u.); at
 0.774
 A
 > (1.463  a.u.) ?  Unfortunately, most programs probably aren't parameterized
 > for helium, in the mistaken belief that it can't form strong bonds.
 > (I can do _ab initio_ calculations on this molecule; but I have a reason
 for
 > wanting the extended Hueckel result).
 >
 >   Thanks
 >
 >    E. Lewars
              -----------------------------------------------------
                             Dr. Satyam Priyadarshy
                     107D, Chevron, Department of Chemistry
              University of Pittsburgh, Pittsburgh, PA 15260, U.S.A
              Fon/Fax: +1-412-624-8200(Extn 1217or 8589) / 624-8552
              email: satyam+ { *at * } pitt.edu OR satyam { *at * }
 hathi.chem.pitt.edu
              -----------------------------------------------------
 =============
 #8
 >From rene { *at * } mountain.chem.yorku.ca Fri Nov  7 14:54:52 EST 1997
 Date: Fri, 7 Nov 1997 14:49:00 -0500 (EST)
 >From: Rene Fournier <rene { *at * } mountain.chem.yorku.ca>
 To: elewars { *at * } alchemy.chem.utoronto.ca
 Subject: STOs
 Dear Dr. Lewars:
    I am also interested in how to calculate overlap (and maybe
 other matrix elements, e.g., kinetic energy) from STOs.  Please
 post (or send me) a summary.
    My *impression* is that calculating any integral involving
 STOs is so complicated that the best practical solution may simply
 be to use a multicenter numerical integration method, such as was
 described by Becke some years ago, and which is now in widespread
 use in DFT (where numerical integration CAN NOT be avoided).
 For a diatomic that would amount more or less to taking the product
 STO(r_i;A)*STO(r_i;B) for i=1,2000 (roughly 2000 quadrature points);
 it's rather time consuming, but a lot simpler than what I've seen of
 "analytical STO" integral algorithms, and maybe even more
 efficient?!?!?
 If efficiency is not an issue for your problem, and you can tolerate
 errors of, say, one part per million, than numerical integration would
 seem best.
 -- Rene Fournier.
  --------------------------------------------------------------------
  | Rene Fournier                  | Bureau/Office  303 Petrie       |
  | Chemistry,  York University    |      (416) 736 2100 Ext. 30687  |
  | 4700 Keele Street, North York  | FAX: (416) 736-5936             |
  | Ontario, CANADA   M3J 1P3      | e-mail: renef { *at * } yorku.ca          |
  --------------------------------------------------------------------
 ===========
 #9
 >From chburger { *at * } aci.unizh.ch Fri Nov  7 16:34:24 EST 1997
 >From: "Dr. Peter Burger" <chburger { *at * } aci.unizh.ch>
 Subject: Re: CCL:SLATER ORBITALS-THANKS AND A REQUEST
 To: elewars { *at * } alchemy.chem.utoronto.ca (E. Lewars)
 Date: Fri, 7 Nov 1997 22:34:19 +0100 (MET)
 Hi,
 here do come your EHT results on HHe+
 Have fun!
 Peter
 ---------------------
 Peter Burger
 Anorg.-Chem. Institut
 Universitaet Zuerich
 chburger { *at * } aci.unizh.ch
         *********************************************************
         *     Carlo MEALLI and Davide M. PROSERPIO (1990)       *
         *      EHC (Extended Huckel Calculation program)        *
         *   A major revision of the original program SIMCON     *
         *         Roald Hoffmann, Cornell University            *
         *    Symmetry routines written by Klaus Linn (1991)     *
         *   New revisions by A. Sironi and J.A. Lopez (1992)    *
         * Ref.: Journal of the Chemical Education (1990,67,399) *
         *********************************************************
 hhe+ 77.4 pm                        ST. 1
     ==== DISTANCE MATRIX.  (values X 10**3)====
        H  1 He  2
  H  1     0
 He  2   774     0
 ========================================================================
 *****************************************************************************
 !!!!!!!   Control+BREAK for interrupting the program    !!!!!!
 $w2o2.in                         ST. 1     .00     .00     .00     .00
 EXTENDED HUCKEL CALCULATION (WEIGHTED HIJ FORMULA)
  ATOM      X      Y      Z N EXP-S  COUL-S N EXP-P  COUL-P N EXPD1  COUL-D    C1
     C2 EXPD2
  H  1   .000   .000   .000 1 1.300 -13.600
 He  2   .000   .000   .774 1 1.300 -10.600
 CHARGE =  1   ELECTRONS =   2
 HUCKEL CONSTANT =   1.750   **** POINTGROUP = Civ ****
 This run requires         124 bytes for the matrices
 Matrix Factorized according to symmetry Ci
 ENERGY LEVELS (EV).
 E(  1) =   2.784    .000    2a1     E(  2) = -15.816   2.000    1a1
         SUM OF ONE-ELECTRON ENERGIES =       -31.63190 EV.
 REDUCED OVERLAP POPUL. MATRIX, ATOM BY ATOM (10**3)
         H  1 He  2
  H  1    899
 He  2    718   381
 TOTAL ELECTRONS=    2  SUM OF: OP(I,I)=   1.281 ( 64.055%)
                                OP(I,J)=    .719 ( 35.945%)
 ATOM     NET CHG.     ATOMIC ORBITAL OCCUPATION FOR  GIVEN MO OCCUPATION
                       S     Px     Py     Pz  x2-y2     z2     xy     xz     yz
  H  1    -.259    1.259
 He  2    1.259     .741
    * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
  * * * * * * * * * * * * * *
 EHMO execution time:          .05 seconds.
 Stop - Program terminated.
         *********************************************************
         *     Carlo MEALLI and Davide M. PROSERPIO (1990)       *
         *      EHC (Extended Huckel Calculation program)        *
         *   A major revision of the original program SIMCON     *
         *         Roald Hoffmann, Cornell University            *
         *    Symmetry routines written by Klaus Linn (1991)     *
         *   New revisions by A. Sironi and J.A. Lopez (1992)    *
         * Ref.: Journal of the Chemical Education (1990,67,399) *
         *********************************************************
 hhe+ 80 pm                        ST. 1
     ==== DISTANCE MATRIX.  (values X 10**3)====
        H  1 He  2
  H  1     0
 He  2   800     0
 ========================================================================
 *****************************************************************************
 !!!!!!!   Control+BREAK for interrupting the program    !!!!!!
 $w2o2.in                         ST. 1     .00     .00     .00     .00
 EXTENDED HUCKEL CALCULATION (WEIGHTED HIJ FORMULA)
  ATOM      X      Y      Z N EXP-S  COUL-S N EXP-P  COUL-P N EXPD1  COUL-D    C1
     C2 EXPD2
  H  1   .000   .000   .000 1 1.300 -13.600
 He  2   .000   .000   .800 1 1.300 -10.600
 CHARGE =  1   ELECTRONS =   2
 HUCKEL CONSTANT =   1.750   **** POINTGROUP = Civ ****
 This run requires         124 bytes for the matrices
 Matrix Factorized according to symmetry Ci
 ENERGY LEVELS (EV).
 E(  1) =   1.754    .000    2a1     E(  2) = -15.759   2.000    1a1
         SUM OF ONE-ELECTRON ENERGIES =       -31.51737 EV.
 REDUCED OVERLAP POPUL. MATRIX, ATOM BY ATOM (10**3)
         H  1 He  2
  H  1    913
 He  2    704   382
 TOTAL ELECTRONS=    2  SUM OF: OP(I,I)=   1.296 ( 64.788%)
                                OP(I,J)=    .704 ( 35.212%)
 ATOM     NET CHG.     ATOMIC ORBITAL OCCUPATION FOR  GIVEN MO OCCUPATION
                       S     Px     Py     Pz  x2-y2     z2     xy     xz     yz
  H  1    -.266    1.266
 He  2    1.266     .734
    * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
  * * * * * * * * * * * * * *
 EHMO execution time:          .06 seconds.
 Stop - Program terminated.
 ==============
 #10
 >From davide { *at * } stinch10.csmtbo.mi.cnr.it Sat Nov  8 04:30:39 EST 1997
 Date: Sat, 8 Nov 1997 10:26:21 +0100
 >From: davide { *at * } stinch10.csmtbo.mi.cnr.it (Davide Proserpio)
 To: "E. Lewars" <elewars { *at * } alchemy.chem.utoronto.ca>
 Subject: Re:  CCL:SLATER ORBITALS-THANKS AND A REQUEST
 Dear E. Lewars
 here I send you the results form a EHT calculation done with CACAO, using
 you will find all the parameters and WF and more for a set of internuclear dista
 nces.
 Obviously there is no minimum with a standard EHT calculation only with 1s orbit
 als.
 note : all the walues of Wavefunction, Charge Matrix, reduced Ov. Pop, Bond orde
 rs
 are multiplied *1000
 regards
              Davide
          *********************************************************
          *     Carlo MEALLI and Davide M. PROSERPIO (1990)       *
          *      EHC (Extended Huckel Calculation program)        *
          *   A major revision of the original program SIMCON     *
          *         Roald Hoffmann, Cornell University            *
          *    Symmetry routines written by Klaus Linn (1991)     *
          *   New revisions by A. Sironi and J.A. Lopez (1992)    *
          * Ref.: Journal of the Chemical Education (1990,67,399) *
          *********************************************************
 RESULTS:  EL's INTERPRETATION/SUMMARY OF OUTPUT OF ABOVE:
                 #1---#6
 ------------------
   H  1     0                            DIST     #1  E = -49.8
  HE  2   852     0   <------------------0.852 A  psi_1 c's: 0.300, 0.822
  DU -1   426   426     0
  ========================================================================
 $# molecular H-He+    with FMO   ST. 2   0.413
 ----------------------------
   H  1     0                            DIST     #2   E = -50.0
  HE  2   826     0    <-----------------0.826 A  psi_1 c's 0.304, 0.814
  DU -1   413   413     0
  ========================================================================
   H  1     0                            DIST     #3   E = -50.1
  HE  2   800     0    <-----------------0.800 A  psi_1 c's: 0.308, 0.807
  DU -1   400   400     0
  ========================================================================
   H  1     0
  HE  2   774     0   <----------------  DIST     #4   E = -50.3
  DU -1   387   387     0                0.774 A  psi_1 c's: 0.311, 0.800
  ========================================================================
   H  1     0
  HE  2   748     0   <----------------- DIST     #5   E = -50.4
  DU -1   374   374     0                0.748 A  psi_1 c's: 0.314, 0.793
  ========================================================================
   H  1     0
  HE  2   722     0   <------------------DIST     #6   E = -50.6
  DU -1   361   361     0                0.722 A  psi_1 c's: 0.317, 0.786
  ========================================================================