[molpro-user] frequencies at a conical intersection ?

[Hans Jakob Woerner]

Dear users,

is it possible to obtain frequencies and normal modes at a conical 
intersection using MOLPRO?
I have successfully optimized the geometry of C5H5+ at the conical 
intersection of the lowest singlet states (using the input given below) but 
no attempt of calculating frequencies suceeded (also using NOSYM).

Best regards,
Hans Jakob

***, C5H5+ geometry optimisation (con. int.) at casscf level after anion rhf
geometry={
Q;
C1, Q, rc;
C2, Q, rc, C1, ac;
C3, Q, rc, C2, ac, C1, dc;
C4, Q, rc, C3, ac, C2, dc;  
C5, Q, rc, C4, ac, C3, dc;
H1, C1, rh, C2, ach, Q, dc;
H2, C2, rh, C3, ach, Q, dc;
H3, C3, rh, C4, ach, Q, dc;
H4, C4, rh, C5, ach, Q, dc;
H5, C5, rh, C1, ach, Q, dc;};
ac=72;
dc=180;
ach=126;
rc=1.18000 ang;
rh=1.0900 ang;
basis=6-31g**;
rhf;wf,36,1,0;          ! anion, a1 ground state, singlet
save, 2100.2;		! save orbitals

maxstep=100
do i=1,maxstep

multi;occ,9,6,3,2;closed,9,6,0,0;
start,2100.2
wf,34,1,0
state,1
wf,34,2,0
state,1

CPMCSCF,GRAD,1.1,spin=0.0,accu=1.0d-7,record=5101.1
CPMCSCF,GRAD,1.2,spin=0.0,accu=1.0d-7,record=5102.1

Force
SAMC,5101.1
CONICAL,6100.1

Force
SAMC,5102.1
CONICAL,6100.1

opt
active, rc, rh

if(optconv.lt.1.d-6) exit

enddo
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