Hello Gonzalo
Generally ASE is calculating dynamic time steps with the Newmark method with numerical damping (as you can see in your graphic).
To deactivate the numerical damping you have to change the parameter of the integration method to
STEP … BET 0.25 DEL 0.50 THE 1.00
Further information can be found in the ASE manual.
TEDDY > Help > manuals > all manuals > ASE > chapter 3.5 STEP -Time Step Method Dynamics
Mit freundlichen Grüßen / with kind regards
SOFiSTiK Support Team
Frederik Höller