Menu drv

The most important of the derivative menus is the first one which tells the programs which derivatives to calculate. This is only necessary for special purposes and you should better not change default options.

------------------------------------------------------------------------
 derivative data groups '$drvopt, $drvtol'
------------------------------------------------------------------------
 option | status  | description :
------------------------------------------------------------------------
 crt    |    T    | CARTESIAN 1st derivatives
 sec    |    T    | CARTESIAN 2nd derivatives
 bas    |    F    | energy derivatives with respect to
        |         |  BASIS SET exponents/scaling factors/
        |         |  contraction coefficients
 glb    |    F    | energy derivative with respect to
        |         |  a GLOBAL scaling factor
 dip    |    T    | cartesian 1st derivatives of DIPOLE MOMENT
 pol    |    T    | nuclear contribution to POLARIZABILITY
 fa     |    F    | SPECTROSCOPIC ANALYSIS only
 tol     0.100D-06  derivative integral cutoff
------------------------------------------------------------------------
 use <opt> for enabling, -<opt> for disabling of logical switches
 <&> will bring you back to GENERAL MENU without more changes
 <RETURN> OR * OR q(uit) WILL TERMINATE THIS MENU

The handling of these options is very simple. With the exception of tol, all are logical switches which are either true (or on, active) or false (or off, inactive). You can switch between the two states if you enter, for example, crt (to switch calculation of Cartesian first derivatives on) or -crt (to switch it off). The options crt, sec and bas should provide no problems. glb refers to a global scaling factor for all basis set exponents. Imagine that you would like to replace your basis set, which contains basis functions

$$\left[\vphantom{-\eta_\mu(r-r_0)^2}\right. \left.\vphantom{-\eta_\mu(r-r_0)^2}\right]$$

by another basis set which contains basis functions

$$\left[\vphantom{-\alpha\eta_\mu(r-r_0)^2}\right. \left.\vphantom{-\alpha\eta_\mu(r-r_0)^2}\right]$$

where α is the same for all primitive basis functions χ_μ. With command glb you are able to calculate analytical derivatives of the total energy with respect to α and can thus easily determine the optimum α.

dip enables you to calculate the first derivatives of the electric dipole moment with respect to nuclear displacements which gives you infrared intensities. pol allows you to calculate the contribution of the nuclear rearrangement on the electric polarizability. fa finally performs only a frequency analysis which means that aoforce will read the force constant matrix ($hessian or $hessian (projected)), diagonalize it and give you the frequencies and normal modes. tol is not a logical switch as the other options in this menu, but a cutoff threshold for the derivative integrals, i.e. integrals below this threshold will be neglected in the derivative calculations.

Entering * will bring you to the second derivative submenu.