[Pw_forum] Temperature continuously going down in cp.x run

[Stefano de Gironcoli]

is the total  (kinetic + potential)  energy conserved ?
stefano

vega lew wrote:
> dear all,
>
> I want to calculate certain heterogeneous reaction on a solid surface.
> First input the initial structure from previous pw.x relaxations.
> Second I fixed ions and let electron damping calculation run;
> Then un-fixed the ions and let both electron  and ions damping 
> calculations run.
> Third I gave a random motion to the atoms in the system with 
> amprp(1)~(3) = 0.01
> and then repeated second step to bring the system to the ground state.
> Fourth I added temperature (300K) to the system, using verlet schedule.
>
> But the temperature continuously going down, from 1000K to 150K during 
> the fisrt 3000 steps.
> I think there might be something wrong with my cp.x calcuation.
> Do you think the amprp(1)~(3) = 0.01 of random motion is too small?
>
> Here is the input of my dynamics process,
>  &CONTROL                                                                                 
>
>                        title = 'CP' 
> ,                                       
>                  calculation = 'cp' 
> ,                                                 
>                 restart_mode = 'restart' 
> ,                                          
>                       outdir = '/disk5/nanjing/vega/cp/300/' ,  
>                       wfcdir = '/tmp/' 
> ,                                                 
>                   pseudo_dir = 
> '/home/software/nanjing/vega/espresso-4.0.1/pseudo/' ,    
>                       prefix = 'cp_molecular' ,
>                        nstep = 99999 ,
>                           dt = 10,
>                       iprint = 5,
>                        isave = 
> 150,                                                     
>  /                                                                                        
>
>  &SYSTEM                                                                                  
>
>                        ibrav = 
> 8,                                                        
>                    celldm(1) =24.8624,
>                    celldm(2) = 0.8520,
>                    celldm(3) = 1.6964,
>                          nat = 
> 147,                                                      
>                         ntyp = 3,
>                         nr1b = 20,
>                         nr2b = 20,
>                         nr3b = 20,
>                         nbnd = 
> 630,                                                        
>                    ecutwfc   =   30,
>                    ecutrho   =  300,
>  /                                                                              
>
>          
>  &ELECTRONS                         
>            electron_dynamics = 'verlet',                        
>  /                                                                             
>
>  &IONS                                                                                    
>
>                 ion_dynamics = 'verlet'
>              ion_temperature = 'nose',         
>                        tempw = 300,         
>  /
> ..................
> ..................
>
> best wishes,
>
> vega
>
> -- 
> ==================================================================================
> Vega Lew ( weijia liu)
> Graduate student
> State Key Laboratory of Materials-oriented Chemical Engineering
> College of Chemistry and Chemical Engineering
> Nanjing University of Technology, 210009, Nanjing, Jiangsu, China
> ******************************************************************************************************************
> Email: vegalew at gmail.com <mailto:vegalew at gmail.com>
> Office: Room A705, Technical Innovation Building, Xinmofan Road 5#, 
> Nanjing, Jiangsu, China  
> ****************************************************************************************************************** 
>
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>
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