How To Perform a Calculation

As presently no gradients are available, only single–point calculations are possible:

1.

Select in define within the menu cc

• the wavefunction model (submenu ricc2),
• frozen core options (submenu freeze),
• an auxiliary basis for $cbas (submenue cbas),
• the amount of main memory (option memory),

and for CCSD(F12) calculations in addition

• the F12 options (submenu f12), and
• a CABS basis (submenu cabs).

By default a CCSD(F12) with ansatz 2 and geminal amplitudes fixed by the cusp conditions is performed. To switch to the computationally more efficient recommended CCSD(F12*) approximation add to the input group $rir12 the line^†

     ccsdapprox  ccsd(f12*)  
         

The auxiliary JK basis must be chosed in menu rijk and the exponent for the correlation function must set by editing the $lcg data group of the control file.

2.

Do an SCF calculations using either the dscf or the ridft module.

3.

Invoke the ccsdf12 program on the command line or with a batch script.