MOLPRO

39 THE VB PROGRAM CASVB 290
to write these vectors to the standard output. If iwrite is negative, then the vectors are instead
written to a binary file as a single record.
SPECIAL,idim1,idim2,idim3,idim4;
If present, this keyword must come last. The program attempts to retrieve from record.file a
vector of length idim1*idim2+idim3, after first skipping idim4 elements. The vector is written
according to the setting of iwrite. (Default idim values are zero.)
39.15 Examples
***, ch2 ! A1 singlet state
geometry={angstrom
c
h1,c,1.117
h2,c,1.117,h1,102.4}
int
hf
{multi;occ,4,1,2;closed,1 ! 6 in 6 CASSCF
natorb,,ci,save=3500.2;vbdump}
{casvb
! Overlap-based VB using
save,3200.2}
! the spin-coupled wavefunction
{casvb
! Energy-based VB calculation
start,,3200.2;save,3220.2
crit,energy}
{multi;occ,4,1,2;closed,1 ! Fully variational VB calculation
{vb;start,,3220.2;save,3240.2;print,,,,,2}}
---
memory,4,m
***,n2s2 (model a)
! Variational calculation for N2S2.
geometry={x,y,z;
a1,n,-2.210137753,0,0; ! NOTE: other choices of active space
a2,n,+2.210137753,0,0; ! give alternative (competing) models.
a3,s,0,-2.210137753,0;
a4,s,0,+2.210137753,0}
basis=VTZ;
cartesian
{hf;wf,46,1}
{multi;occ,7,4,5,2,4,2,2,0;closed,7,4,5,2,1,0,1,0; natorb,,ci,save=3500.2}
{multi;occ,7,4,5,2,4,2,2,0;closed,7,4,5,2,1,0,1,0; vb}
---
***, lih ! Fully variational VB calculation
r=2.8,bohr
! and geometry optimization.
basis={
s,1,921.300000,138.700000,31.940000,9.353000,3.158000,1.157000;
k,1.6,0.001367,0.010425,0.049859,0.160701,0.344604,0.425197;
s,1,0.444600,0.076660,0.028640;
p,1,1.488000,0.266700,0.072010,0.023700;
k,1.2,0.038770,0.236257;
s,2,13.36,2.013,0.4538,.1233;