Subject: Gaussian Z-Matrices

From: Heather Horton <[email-masked]>
Date: Tue, 17 Sep 1996 11:03:08 -0500 (CDT)

Hi Netters!

	My evil boss gave me the assignment of calculating points
with Gaussian 94, but I don't have the manual!  I created the
Z matrix for CH4 and NH3 on my own and ran them.  Here is a
listing of the partial output:

For CH4 I got --

 **************************************************
 Gaussian 94:  CrayXMP-Unicos-G94RevD.3  1-May-1996
                    22-Jul-1996
 **************************************************
 %chk=ch4
 -----------------
 #RHF/6-31G** Test
 -----------------
 1/38=1/1;
 2/12=2,17=6,18=5/2;
 3/5=1,6=6,7=101,11=1,25=1,30=1/1,2,3;
 4/7=1/1;
 5/5=2,32=1,38=4/2;
 6/7=2,8=2,9=2,10=2,19=1,28=1/1;
 99/5=1,9=1/99;
 ----------------------------
 Single point CH4 calculation
 ----------------------------
 Symbolic Z-matrix:
    Charge = 0 Multiplicity = 1
 C
 H     1     RCH1
 H     1     RCH2      2     DTET
 H     1     RCH3      2     DTET      3     DIHE      0
 H     1     RCH4      2     DTET      3     -DIHE     0
       Variables:
  RCH1                  1.                       
  RCH2                  1.                       
  RCH3                  1.                       
  RCH4                  1.25                     
  DIHE                120.                       
  DTET                109.5                      
 ------------------------------------------------------------------------
                         Z-MATRIX (ANGSTROMS AND DEGREES)
 CD Cent Atom  N1     Length/X     N2    Alpha/Y     N3     Beta/Z      J
 ------------------------------------------------------------------------
   1   1  C 
   2   2  H     1   1.000000(  1)
   3   3  H     1   1.000000(  2)   2  109.500(  5)
   4   4  H     1   1.000000(  3)   2  109.500(  6)   3  120.000(  8)   0
   5   5  H     1   1.250000(  4)   2  109.500(  7)   3 -120.000(  9)   0
 ------------------------------------------------------------------------
                  Z-Matrix orientation:
 ----------------------------------------------------------
 Center     Atomic              Coordinates (Angstroms)
 Number     Number             X           Y           Z
 ----------------------------------------------------------
    1          6           0.000000    0.000000    0.000000
    2          1           0.000000    0.000000    1.000000
    3          1           0.942641    0.000000   -0.333807
    4          1          -0.471321   -0.816351   -0.333807
    5          1          -0.589151    1.020439   -0.417259
 ----------------------------------------------------------
                    Distance matrix (angstroms):
              1          2          3          4          5
  1  C    0.000000
  2  H    1.000000   0.000000
  3  H    1.000000   1.633283   0.000000
  4  H    1.000000   1.633283   1.632703   0.000000
  5  H    1.250000   1.843100   1.842457   1.842457   0.000000
                           Interatomic angles:
       H2-C1-H3=109.5          H2-C1-H4=109.5          H3-C1-H4=109.4424
       H2-C1-H5=109.5          H3-C1-H5=109.4424       H4-C1-H5=109.4424
 Stoichiometry    CH4
 Framework group  CS[SG(CH2),X(H2)]
 Deg. of freedom    6
 Full point group                 CS      NOp   2
 Largest Abelian subgroup         CS      NOp   2
 Largest concise Abelian subgroup CS      NOp   2
                   Standard orientation:
 ----------------------------------------------------------
 Center     Atomic              Coordinates (Angstroms)
 Number     Number             X           Y           Z
 ----------------------------------------------------------
    1          6           0.000000    0.025048    0.000000
    2          1           0.940843    0.363889    0.000000
    3          1          -0.473763    0.355379    0.816351
    4          1          -0.473763    0.355379   -0.816351
    5          1           0.006683   -1.224934    0.000000
 ----------------------------------------------------------

And, for NH3 I got --

 **************************************************
 Gaussian 94:  CrayXMP-Unicos-G94RevD.3  1-May-1996
                    30-Jun-1996
 **************************************************
 %chk=nh3
 -----------------
 #RHF/6-31G** Test
 -----------------
 1/38=1/1;
 2/12=2,17=6,18=5/2;
 3/5=1,6=6,7=101,11=1,25=1,30=1/1,2,3;
 4/7=1/1;
 5/5=2,32=1,38=4/2;
 6/7=2,8=2,9=2,10=2,19=1,28=1/1;
 99/5=1,9=1/99;
 ----------------------------
 Single point NH3 calculation
 ----------------------------
 Symbolic Z-matrix:
    Charge = 0 Multiplicity = 1
 N
 X1    N     RX
 H1    N     RNH       X1    DUMB
 H2    N     RNH       X1    DUMB      H1    DIHE      0
 H3    N     RNH       X1    DUMB      H1    -DIHE     0
       Variables:
  RX                    1.02                     
  RNH                   1.02                     
  DIHE                120.                       
  DUMB                108.                       
 ------------------------------------------------------------------------
                         Z-MATRIX (ANGSTROMS AND DEGREES)
 CD Cent Atom  N1     Length/X     N2    Alpha/Y     N3     Beta/Z      J
 ------------------------------------------------------------------------
   1   1  N 
   2      X     1   1.020000(  1)
   3   2  H     1   1.020000(  2)   2  108.000(  5)
   4   3  H     1   1.020000(  3)   2  108.000(  6)   3  120.000(  8)   0
   5   4  H     1   1.020000(  4)   2  108.000(  7)   3 -120.000(  9)   0
 ------------------------------------------------------------------------
                  Z-Matrix orientation:
 ----------------------------------------------------------
 Center     Atomic              Coordinates (Angstroms)
 Number     Number             X           Y           Z
 ----------------------------------------------------------
    1          7           0.000000    0.000000    0.000000
    2         -1           0.000000    0.000000    1.020000
    3          1           0.970078    0.000000   -0.315197
    4          1          -0.485039   -0.840112   -0.315197
    5          1          -0.485039    0.840112   -0.315197
 ----------------------------------------------------------
                    Distance matrix (angstroms):
              1          2          3          4          5
  1  N    0.000000
  2  X    1.020000   0.000000
  3  H    1.020000   1.650395   0.000000
  4  H    1.020000   1.650395   1.680224   0.000000
  5  H    1.020000   1.650395   1.680224   1.680224   0.000000
                           Interatomic angles:
       X2-N1-H3=108.           X2-N1-H4=108.           H3-N1-H4=110.9015
       X2-N1-H5=108.           H3-N1-H5=110.9015       H4-N1-H5=110.9015
 Stoichiometry    H3N
 Framework group  C3V[C3(N),3SGV(H)]
 Deg. of freedom    2
 Full point group                 C3V     NOp   6
 Largest Abelian subgroup         CS      NOp   2
 Largest concise Abelian subgroup CS      NOp   2
                   Standard orientation:
 ----------------------------------------------------------
 Center     Atomic              Coordinates (Angstroms)
 Number     Number             X           Y           Z
 ----------------------------------------------------------
    1          7           0.000000    0.000000    0.094559
    2          1           0.000000    0.970078   -0.220638
    3          1           0.840112   -0.485039   -0.220638
    4          1          -0.840112   -0.485039   -0.220638
 ----------------------------------------------------------

I have two questions about these:

(1)  First, how do I change the input so I can run multiple
geometries at once?  For example, I would like to change
a bond length from 0.8 Angstroms to 1.6 Angstroms in increments
of 0.1 Angstroms?  

(2)  I ran these SYMMETRIC cases for CH4 and NH3 to see if
my input deck was correct?  But, I was surprised to see that 
when Gaussian 94 calculated the Interatomic angles they didn't
have the symmetry I expected.  Notice in NH3 that the H-N-H
bond angles are not 111 degrees like I had expected.
Am I misunderstanding this?

Thanks everybody, HH

p.s.  shouldn't these last 2 H-C-H bond angles for CH4
be 109.5 too???

       H2-C1-H5=109.5          H3-C1-H5=109.4424       H4-C1-H5=109.4424