Download MOLPRO

13
RELATIVISTIC CORRECTIONS
***,Na2
! Potential curve of the Na2 molecule
! using 1-ve ECP + CPP
gprint,basis,orbitals;
rvec=[2.9,3.0,3.1,3.2,3.3] ang
do i=1,#rvec
rNa2=rvec(i)
geometry={na;na,na,rNa2}
basis={
ecp,na,ecp10sdf;
! ecp input
s,na,even,8,3,.5;
! basis input
p,na,even,6,3,.2;
d,na,.12,.03;
}
cpp,init,1;
! CPP input
na,1,.9947,,,.62;
hf;
ehf(i)=energy
cisd;core;
eci(i)=energy
enddo
table,rvec,ehf,eci
---
13
82
examples/
na2_ecp_cpp.com
RELATIVISTIC CORRECTIONS
There are three ways in M OLPROto take into account scalar relativistic effects:
1. Use the Douglas-Kroll relativistic one-electron integrals.
2. Compute a perturbational correction using the Cowan-Griffin operator (see section 4.13).
3. Use relativistic effective core potentials (see section 11).
For all-electron calculations, the prefered way is to use the Douglas-Kroll Hamiltonian. It is
simply activated by setting
DKROLL=1
somewhere in the input before the first energy calculation.
13.0.1
Example for computing relativistic corrections
***,ar2
geometry={ar1;ar2,ar1,r}
r=2.5 ang
hf;
expec,rel,darwin,massv
e_nrel=energy
show,massv,darwin,erel
!geometry definition
!bond distance
!non-relativisitic scf calculation
!compute relativistic correction using Cowan-Griffin operator
!save non-relativistic energy in variable enrel
!show individual contribution and their sum
dkroll=1
hf;
e_dk=energy
show,massv,darwin,erel
show,e_dk-e_nrel
examples/
!use douglas-kroll one-electron integrals
ar2_rel.com
!relativistic scf calculation
!save relativistic scf energy in variable e_dk.
!show mass-velocity and darwin contributions and their sum
!show relativistic correction using Douglas-Kroll