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## 65.27 Exercise: SCF program

Write a closed-shell SCF program for HO using MATROP!

Hints:

First generate a starting orbital guess by finding the eigenvectors of h0. Store the orbitals in a record. Basis and geometry are defined in the usual way before the first call to MATROP.

Then use a MOLPRO DO loop and call MATROP for each iteration. Save the current energy in a variable (note that the nuclear energy is stored in variable ENUC). Also, compute the dipole moment in each iteration. At the end of the iteration perform a convergence test on the energy change using the IF command. This must be done outside MATROP just before the ENDDO. At this stage, you can also store the iteration numbers, energies, and dipole moments in arrays, and print these after reaching convergence using TABLE. For the following geometry and basis set

```geometry={o;h1,o,r;h2,o,r,h1,theta}   !Z-matrix geometry input
r=1 ang                               !bond length
theta=104                             !bond angle
basis=vdz                             !basis set
thresh=1.d-8                          !convergence threshold
```

the result could look as follows:

``` SCF has converged in 24 iterations

ITER       E             DIP
1.0   -68.92227207    2.17407361
2.0   -71.31376891   -5.06209922
3.0   -73.73536433    2.10199751
4.0   -74.64753557   -1.79658706
5.0   -75.41652680    1.43669203
6.0   -75.77903293    0.17616098
7.0   -75.93094231    1.05644998
8.0   -75.98812258    0.63401784
9.0   -76.00939154    0.91637513
10.0   -76.01708679    0.76319435
11.0   -76.01988143    0.86107911
12.0   -76.02088864    0.80513445
13.0   -76.02125263    0.83990621
14.0   -76.02138387    0.81956198
15.0   -76.02143124    0.83202128
16.0   -76.02144833    0.82464809
17.0   -76.02145450    0.82912805
18.0   -76.02145672    0.82646089
19.0   -76.02145752    0.82807428
20.0   -76.02145781    0.82711046
21.0   -76.02145792    0.82769196
22.0   -76.02145796    0.82734386
23.0   -76.02145797    0.82755355
24.0   -76.02145797    0.82742787
```

It does not converge terribly fast, but it works!

Next: 66 Post-processing of output Up: 65 MATRIX OPERATIONS Previous: 65.26 Examples   Contents   Index

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molpro@molpro.net 2018-06-21