MOLPRO

46 BASIS SET EXTRAPOLATION 348
46.3 Geometry optimization using extrapolated energies
Geometry optimizations are possible by using numerical gradients obtained from extrapolated
energies. Analytical energy gradients cannot be used.
The following possibilities exist:
1.) If OPTG directly follows the EXTRAPOLATE command, the extrapolated energy is optimized
automatically (only variable settings may occur between EXTRAPOLATE and OPTG).
Examples:
Extrapolating the energy for the last command:
geometry={o;h1,o,r;h2,o,r,h1,theta}
theta=102
r=0.96 ang
basis=vtz
hf
ccsd(t)
extrapolate,basis=vtz:vqz
optg
http:
//www.molpro.net/info/current/examples/h2o_extrapol_opt1.com
Extrapolating the energy computed in a procedure:
geometry={o;h1,o,r;h2,o,r,h1,theta}
theta=102
r=0.96 ang
proc ccsdt
hf
ccsd(t)
endproc
extrapolate,basis=vtz:vqz,proc=ccsdt
optg
http:
//www.molpro.net/info/current/examples/h2o_extrapol_opt2.com
Note that this is not possible if EXTRAPOLATE gets the input energies from variables.