sub group symmetry

[Jacky LIEVIN]

Dear all,

I wonder if anything has changed in the use of the symmetry command since the molpro2015 version? Old input files using the symmetry command for imposing a subgroup symmetry doesn’t seem to work anymore with molpro2020.
For instance in this simple example, the second calculation doesn’t use the requested Cs symmetry, but keeps C2v symmetry:

r=1 ang
a=100 degrees
geometry={o;h1 o r;h2 o r h1 a }
rhf
symmetry,X
rhf

I’ve tried to recopy the geometry block after the symmetry command, but this does’t help.

Thanks for any advice,

Jacky

[Hans-Joachim Werner]

Dear Jacky,

symmetry is also a directive of rhf and this ambiguity is not detected by the input checker. I’ll try to fix that. You need to use curley brackets:

{rhf}
symmetry,x
{rhf}

then it works.
Best wishes
Joachim

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[Jacky LIEVIN]

Dear Joachim,

Thanks for your quick answer.

Unfortunately, this doesn’t solve the more complex case I’m interested in. The following input works on molpro2015, but reports a bug on 2020/21:

rcc=1.252,ang
rch=1.078,ang
rcchalf=rcc*0.5
alpha=180.0
geometry={
N1
C1,N1,rcchalf
DU1,N1,0.1,C1,90
DU2,N1,0.1,C1,90,DU1,90
C2,N1,rcchalf,DU1,90,C1,180
H1 C1 rch C2 alpha DU1 0
H2 C2 rch C1 alpha DU1 180}
basis
spdf,C,vtz;c;
sp,H,vtz;c;
p,N,even,5,2.2,0.01 ;
endbasis
dummy,1
{rhf
occ,3,1,1,,2
wf,13,3,1;}
! linear D2h symmetry
{multi
occ,3,2,2,,4,1,1
closed,2,,,,2
wf,14,1;state,3
wf,14,4;state,2
wf,14,6;state,1
wf,14,7;state,1
orbital,2400.2
expec2,Lzz}
! C2h subgroup symmetry
symmetry,X,YZ
{multi
closed,2,,2;occ,4,2,6,1
wf,14,1;state,4;
wf,14,4;state,3;
start,2400.2
expec2,lzz}

Here is the error message:

Attempt to include non-existent symmetry XY

Z matrix z matrix
========

Records: 700.0 700.0 700.0
Maximum, total, and current numbers of geometry points 100 1 1
Orientation using atomic masses
Molecule type: Linear
User-specified symmetry elements: Z,XY
Symmetry elements: Z
...

This should not happen .. please report as a bug
User-specified symmetry elements: Z,XY
Symmetry elements: Z
? Error
? Symmetry error
? The problem occurs in zmatrix.f:zmat_evaluate

Best wishes

Jacky

[Alexander Mitrushchenkov]

Hi Jacky,

You should repeat the geometry block after symmetry statement. Also, it
is always better to put brackets around symmetry, i.e. {symmetry,x,yz}.
Then your job is fine.

Best,

Alexander

--
Dr. Alexander Mitrushchenkov, IGR
Laboratoire de Modélisation et Simulation Multi Echelle
UMR 8208 CNRS
Univ Gustave Eiffel
5 Bd Descartes
77454 Marne la Vallée, Cedex 2, France

Phone: +33(0)160957316
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e-mail: Alexander.Mi...@univ-eiffel.fr