Unit of displacements in TURBOMOLE

[basklau]

Hi!

I'm wondering what the units of the cartesian displacements in an aoforce calcuation are? a_0, Angstrom oder something completely different?

basklau

[uwe]

Hello,

aoforce does the 2nd derivatives analytically, what cartesian displacements do you refer to?

Uwe

[basklau]

The output displacements (normal modes) !

basklau

[uwe]

Hi,

the $vibrational normal modes are the eigenvectors of the Hessian matrix that give the direction of the modes. The vectors are for displacement in the limit -> 0 so to say.

To get coordinates that are moved along a mode, use the script screwer.

Regards,

Uwe

[basklau]

Thank you! That helps!

What are the cartesian gradients printed out by screwer?


basklau

[uwe]

Hi,

those from the gradient file - current coordinates, newest gradients from the last gradient calculation or geometry optimization, and the vibrational normal modes are read in to generate the new shifted coordinates.

Uwe

[basklau]

What exactly is this program vibrations doing? 

Greeting basklau

[uwe]

Hi,

it reads in the vibrational normal modes and moves the coordinates along the mode that one can choose. The new coordinates can then for example be used to start a new optimization - useful if you want to get rid of an imaginary frequency.

Regards,

Uwe