MOLPRO

42 GEOMETRY OPTIMIZATION (OPTG) 328
***, HCN NHC Isomerization Reaction Path
memory,1,m
basis=3-21G
rcn=1.18282 ang
rnh=1.40745 ang
alpha=55.05 degree
! Starting geometry is transition state
symmetry,x
! Cs Symmetry
geometry={
C
N,1,rcn
H,2,rnh,1,alpha}
int
rhf
optg,root=2,saveact=hcn_ts,rewind
! Find and store the TS
{optg,method=qsdpath,dir=1, numhess=5,hesscentral,saveact=hcn_path}
! find IRC in posi
readvar,hcn_ts.act
! Reset geometry to TS
{optg,method=qsdpath,dir=-1,numhess=5,hesscentral,saveact=hcn_path,append} !find IRC in negati
readvar,hcn_path.act
alpha=alpha*pi/180
!convert angle to radian
table,irc,rcn,rnh,alpha,e_opt
{table,irc,e_opt
plot,file=’hcn_eopt.plot’}
{table,irc,rcn,rnh,alpha
plot,file=’hcn_dist.plot’}
!tabulate results
!plot energy profile as function of irc
!plot distances and angle as function of irc
http:
//www.molpro.net/info/current/examples/hcn_isomerization.com
This produces the plots
-92.24
-92.26
-92.28
E_OPT
-92.3
-92.32
-92.34
-92.36
-3 -2 -1 0 1 2
IRC