[Pw_forum] temperature control in PWscf

[Eric Schwegler]

Alain,
I've run into this as well. It seems to me that in version 3.0, 
dynamics.f90 does not save the
velocities between MD timesteps. So after the initial velocity scaling 
they are basically set
to zero. Simply adding the vel array to the unit=4 read and write 
statements in dynamics.f90
seems to fix the problem for me. Is this a known bug?
-Eric Schwegler



> Dear all,
> I am trying to perform a temperature rescaling MD with PWscf
>
> &IONS
>     ion_dynamics = 'verlet'
>     ion_temperature = 'rescaling'
>     tempw = 500.0
>     nraise = 1
>     tolp = 1.d-8
>     wfc_extrapolation = 'first_order'
> /
>
> The starting temperature is correct but it decreases very rapidly
>
> 358:     Starting temperature  =   500.00 K
> 405:     temperature           =   496.70493449 K
> 693:     temperature           =     0.24166052 K
> 903:     temperature           =     0.21332563 K
> 1113:     temperature           =     0.18863928 K
> 1323:     temperature           =     0.16711531 K
> 1533:     temperature           =     0.14835294 K
> 1743:     temperature           =     0.13194319 K
> 1953:     temperature           =     0.11759977 K