# **WAVE FUNCTION¶

## Get the wave function¶

This section allows the specification of which wave function module(s) to activate. By default no modules are activated. To activate any of these modules you must also specify .WAVE FUNCTION under **DIRAC, otherwise this input is not read.

Note that the order below specifies the order in which the different modules are called if you ask for more than one.

### .SCF¶

Activates the Hartree-Fock/Kohn-Sham module.

Specification of the SCF module can be given in the *SCF subsection.

If .DFT has been specified under **HAMILTONIAN, then a Kohn-Sham calculation will be performed, otherwise a Hartree-Fock calculation will be performed.

### .RESOLVE¶

Resolve open-shell states: do a small CI calculation to get the individual energies of the states present in an average-of-configurations open-shell Hartree-Fock calculation (see *RESOLVE).

### .MP2¶

Activates .MP2CAL.

### .MVO¶

Calculate modified virtual orbitals (see MVOCAL).

### .MP2 NO¶

Activates the *MP2 NO module to calculate MP2 natural orbitals.

### .RELCCSD¶

Activates the RELCCSD (and the MOLTRA module to get 4-index transformed integrals).

By default, molecular orbitals with orbital energy between -10 and +20 hartree (a.u.) are included, this can be modified in the MOLTRA section.

### .DIRRCI¶

Activates the MOLFDIR CI module (and also the MOLTRA module to get 4-index transformed integrals).

Specification of input for the MOLFDIR CI module is given in the DIRRCI – Direct CI module and GOSCIP – COSCI module sections.

By default, molecular orbitals with orbital energy between -10 and +20 hartree (a.u.) are included, this can be modified in the MOLTRA section.

### .LUCITA¶

Activates the *LUCITA (and the **MOLTRA module to get 4-index transformed integrals).

By default, molecular orbitals with orbital energy between -10 and +20 hartree (a.u.) are included, this can be modified in the **MOLTRA section.

## Pre-SCF orbital manipulations¶

### .REORDER MO¶

Interchange initial molecular orbitals prior to the SCF-calculation. The start orbitals from DFCOEF are read and reordered.

For each fermion irrep give the new order of orbitals.

Example:

.REORDER MO'S
1..8,10,9

### .ORBROT¶

Jacobi rotations between pairs of orbitals.

On the line following the keyword, give first the rotation angle, then on the following line(s) for each fermion irrep, give an Specification of orbital strings of orbitals to rotate.

## Post-SCF orbital manipulations¶

### .POST SCF REORDER MO¶

Interchange converged molecular orbitals. The orbitals from DFCOEF are read and reordered just before exiting the SCF subroutine.

For each fermion irrep give the new order of orbitals.

Example:

.POST DHF REORDER MO'S
1..8,10,9

### .PHCOEF¶

Phase adjustment of coefficients DFCOEF: make the largest element of a given orbital real and positive.