Subject: G94: problems with ambigious geometry

From: "Kai Leonhard" <[email-masked]>
Date: Tue, 10 Nov 1998 15:29:28 +0100

Hi,

I am trying to study the interaction between 2 N2 molecules with G94. My
problem: G94 produces different results (MP2 energies) for two geometric
configurations which should give the same results because of symmetry
considerations. Also all atom-atom distances are the same for both
configurations, if you adjust the numerical lables of atoms of the 2. run to
those of the 1. run (see below). Does anyone know of a G94 problem that
produces such results?

Here are my geometries:

File 1, Input:

%Mem=40MB
#MP2/aug-cc-pVDZ Scan NoSymm

0 1
 X1  	0	0.0 	0.0 	0.0
 N2	0	0.0	0.0	NNhalb
 N3     0	0.0	0.0	-NNhalb
 X 	1	r	2 	alpha		3	0.0
 N5    	4   	NNhalb	1	beta		2	fi
 N6    	4   	NNhalb	5	180.0		2	0.0

NNhalb	0.56590107
r	7.0
alpha	0.0
beta	45.0
fi	45.0

It gives the following Z-Matrix and energy:
 ------------------------------------------------------------------------
                  Z-Matrix orientation:
 ----------------------------------------------------------
 Center     Atomic              Coordinates (Angstroms)
 Number     Number             X           Y           Z
 ----------------------------------------------------------
    1         -1           0.000000    0.000000    0.000000
    2          7           0.000000    0.000000    0.565901
    3          7           0.000000    0.000000   -0.565901
    4         -1           0.000000    0.000000    7.000000
    5          7           0.400152    0.000000    6.599848
    6          7          -0.400152    0.000000    7.400152
 ----------------------------------------------------------
                    Distance matrix (angstroms):
              1          2          3          4          5
  1  X    0.000000
  2  N    0.565901   0.000000
  3  N    0.565901   1.131802   0.000000
  4  X    7.000000   6.434099   7.565901   0.000000
  5  N    6.611967   6.047200   7.176913   0.565901   0.000000
  6  N    7.410963   6.845956   7.976097   0.565901   1.131802

  SCF Done:  E(RHF) =  -217.905843244     A.U. after   13 cycles
             Convg  =    0.3778D-08             -V/T =  2.0047
             S**2   =   0.0000
  E2 =    -0.6555225370D+00 EUMP2 =    -0.21856136578127D+03

The 2. job uses different angles, input:

%Mem=40MB
#MP2/aug-cc-pVDZ Scan NoSymm

0 1
 X1  	0	0.0 	0.0 	0.0
 N2	0	0.0	0.0	NNhalb
 N3     0	0.0	0.0	-NNhalb
 X 	1	r	2 	alpha		3	0.0
 N5    	4   	NNhalb	1	beta		2	fi
 N6    	4   	NNhalb	5	180.0		2	0.0

NNhalb  0.56590107
r	7.0
alpha	45.0
beta	0.0
fi	0.0

The results:
 ------------------------------------------------------------------------
                  Z-Matrix orientation:
 ----------------------------------------------------------
 Center     Atomic              Coordinates (Angstroms)
 Number     Number             X           Y           Z
 ----------------------------------------------------------
    1         -1           0.000000    0.000000    0.000000
    2          7           0.000000    0.000000    0.565901
    3          7           0.000000    0.000000   -0.565901
    4         -1           4.949747    0.000000    4.949747
    5          7           4.549595    0.000000    4.549595
    6          7           5.349900    0.000000    5.349900
 ----------------------------------------------------------

(in brackets are the lables of the first run)

                    Distance matrix (angstroms):
                 1 (4)     2 (5)      3 (6)      4 (1)      5 (2)
  1 (4) X    0.000000
  2 (5) N    0.565901   0.000000
  3 (6) N    0.565901   1.131802   0.000000
  4 (1) X    7.000000   6.611967   7.410963   0.000000
  5 (2) N    6.434099   6.047200   6.845956   0.565901   0.000000
  6 (3) N    7.565901   7.176913   7.976097   0.565901   1.131802

 SCF Done:  E(RHF) =  -217.905843244     A.U. after   15 cycles
             Convg  =    0.8106D-08             -V/T =  2.0047
             S**2   =   0.0000
 E2 =    -0.6555225399D+00 EUMP2 =    -0.21856136578412D+03

The SCF energies are the same, but the MP2 ones differ.

Yours, Kai Leonhard

e-mail: [email-masked]