How can I ramp a temperature up from a starting low temperature or ramp downward from a high temperature?

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Dev Rana

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Apr 27, 2020, 3:24:50 PM4/27/20
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Hello Friends! Hopefully everyone is staying safe during these crazy times.

I'm modeling metal aluminum conformations and relaxation due to heat.

I'm attempting to take a solid aluminum block (Al) at 298K from crystal and take it to a molten state at 1000K. After some time at 1000K, when the block begins to exhibit equilibrium conditions, I'd like to take it back to a solid room temperature state at 298K. What is the best method to accomplish this? I'm using a CSVR thermostat currently at 1000K. But I'm not sure how to accomplish the annealing (298K to 1000K), quenching (1000K to 298K), and tempering (400K) steps or how to use the annealing function to accomplish all of these three.

Any advice would be fantastic!

Thanks!
Dev

Thomas Kühne

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Apr 27, 2020, 5:29:48 PM4/27/20
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Dear Dev, 

this can be done using TEMPERATURE_ANNEALING. 
Values smaller and larger than 1 are necessary for either 
case. 

Cheers, 
Thomas

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==============================
Thomas D. Kühne
Dynamics of Condensed Matter
Chair of Theoretical Chemistry
University of Paderborn
Warburger Str. 100
D-33098 Paderborn
Germany

Dev Rana

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Apr 27, 2020, 5:58:59 PM4/27/20
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Thanks Thomas!

I'm assuming that values higher than 1 are for annealing, and values lower than 1 are for quenching?

Is there a specific way of using this function either by itself or with a thermostat?

Is there a tutorial or sample code you can refer me to?

Best Regards,
Dev


On Monday, April 27, 2020 at 5:29:48 PM UTC-4, tkuehne wrote:
Dear Dev, 

this can be done using TEMPERATURE_ANNEALING. 
Values smaller and larger than 1 are necessary for either 
case. 

Cheers, 
Thomas

Am 27.04.2020 um 21:24 schrieb Dev Rana <dev....@gmail.com>:

Hello Friends! Hopefully everyone is staying safe during these crazy times.

I'm modeling metal aluminum conformations and relaxation due to heat.

I'm attempting to take a solid aluminum block (Al) at 298K from crystal and take it to a molten state at 1000K. After some time at 1000K, when the block begins to exhibit equilibrium conditions, I'd like to take it back to a solid room temperature state at 298K. What is the best method to accomplish this? I'm using a CSVR thermostat currently at 1000K. But I'm not sure how to accomplish the annealing (298K to 1000K), quenching (1000K to 298K), and tempering (400K) steps or how to use the annealing function to accomplish all of these three.

Any advice would be fantastic!

Thanks!
Dev

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Thomas Kühne

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Apr 27, 2020, 7:26:39 PM4/27/20
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Nope, 

values smaller are for annelaing/quenching, whereas values 
larger than 1 can be used to exponentially increase the 
temperature. The value is used to rescale the temperature, 
which is then used as the target temperature for your 
thermostat. 

Cheers, 
Thomas

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Dev Rana

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Apr 28, 2020, 10:18:36 PM4/28/20
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Hi Thomas,

Thank you very much for your response. Is there a published graph of how the ramp up or ramp down algorithm scales? Is there a reference with the scaling equation?

Best Regards,
Dev
Thomas

Lucas Wu

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Nov 8, 2020, 10:26:36 PM11/8/20
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Hi Thomas,

I'm new to CP2K.
So if I want to cool to 300K, I need to  set TEMPERATURE=300K, and TEMPERATURE_ANNEALING<1?

Best,
Lucas

Matt W

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Nov 9, 2020, 7:31:53 AM11/9/20
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Yes. To my knowledge you can only get exponential cooling exactly as you stated.

Matt

Thomas Kühne

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Nov 9, 2020, 8:29:57 AM11/9/20
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Dear Lucas, 

Matt’s comment is correct. But just to be clear, when you want to anneal to 300 K, you 
better start from a higher value together with TEMPERATURE_ANNEALING<1. 

Cheers, 
Thomas

Dongliang Wu

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Nov 9, 2020, 11:40:04 AM11/9/20
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Dear Thomas,

How do I set the start temperature? Does cp2k have start and end temperature like vasp?

Regards,
Lucas

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