QuantumATK Forum

QuantumATK => General Questions and Answers => Topic started by: leslie on May 23, 2011, 18:21

Title: Restore scf result
Post by: leslie on May 23, 2011, 18:21

Dear all,

I would like to know, in ATK11.2,  how to restore a self-consistent calculation result for further two-probe transport properties calculation given that I already have an  .nc file after scf run for the device system?
 
I have just switch to version 11.2 and find it is quite different from 08.10. In 08.10, we have a function named restoreSelfConsistentCalculation(). What is its equivalence in 11.2?

I would appreciate it if one example is provided together...

Many thanks.
leslie

Title: Re: Restore scf result
Post by: leslie on May 23, 2011, 18:27

By 'example' I mean a full script which restores an old scf result for a two-probe system and then calculates its transport property.

Title: Re: Restore scf result
Post by: Anders Blom on May 23, 2011, 23:25

The equivalent function in 11.2 is nlread(), although it's much more versatile than before. Here's a simple example:

Code: python

scf = nlread("file.nc",DeviceConfiguration)[0]
T = TransmissionSpectrum(scf, energies = ...)
nlprint(T)
print T.current()

There are a couple of ways to use nlread(), check out the manual (http://quantumwise.com/documents/manuals/latest/ReferenceManual/index.html/ref.nlread.html). For instance, if the NC file contains more than one configuration (an I-V scan, say), you should make sure to pick the right one from the list (nlread() always returns a list, even if only one matching object is found in the file), e.g. by using the "object_id" which can be inspected in VNL.

If you want to set up the corresponding script in VNL, use the "Analysis from file" option in the Scripter.

Title: Re: Restore scf result
Post by: leslie on May 24, 2011, 02:27

Thanks, Anders. So we do not need to set the initial spin if it is already set before scf run, right? By nlread the .nc file after scf, the initial spin will be loaded ?

Title: Re: Restore scf result
Post by: Anders Blom on May 24, 2011, 09:28

The initial spin is only used to start the calculation. When loading the NC file you read in not the initial spin but the final spin (that which was determined self-consistently during the calculation), which is what you want :)