# How to Perform Nudge Elastic Bands calculation

**URL:** <https://discourse.abinit.org/t/how-to-perform-nudge-elastic-bands-calculation/3791>\
**Category:** Ground state\
**Created:** [December 22, 2025, 9:02pm UTC](https://discourse.abinit.org/t/how-to-perform-nudge-elastic-bands-calculation/3791 "2025-12-22T21:02:11Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![sms](https://discourse.abinit.org/letter_avatar_proxy/v4/letter/s/ecb155/32.png) [@sms](https://discourse.abinit.org/u/sms)\
**Post date:** [December 22, 2025, 9:02pm UTC](https://discourse.abinit.org/t/how-to-perform-nudge-elastic-bands-calculation/3791/1 "2025-12-22T21:02:11Z")

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Hi,

I want to obtain possible different structure between two different structures of minimum energies using Nudge Elastic Band theory. Can someone share any tutorial on that how to perform these calculations with some simple structures?

Thanks

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**Author:** ![Antonius](https://discourse.abinit.org/user_avatar/discourse.abinit.org/antonius/32/888_2.png) [@Antonius](https://discourse.abinit.org/u/Antonius)\
**Post date:** [January 2, 2026, 9:20pm UTC](https://discourse.abinit.org/t/how-to-perform-nudge-elastic-bands-calculation/3791/2 "2026-01-02T21:20:15Z")

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Hello,

Have a look at the Abinit test files, in particular test v10[83], whose input file can be found in the abinit source directory at `~abinit/tests/v10/Inputs/t83.abi`

Some important input variables for NEB calculations are:

> #Definition of the PATH to explore  
> xred\_img1 0.0 0.0 0.0 # Starting point  
> 1/2 1/2 1/2  
> xred\_lastimg 0.0 0.0 0.0 # End point (distorded positions)  
> 3/2 1/2 1/2 # Atom 2 has moved
> 
> #Nudged Elastic Band parameters
> 
> imgmov 5 # Select NEB method  
> neb\_algo 1 # Improved-tangent NEB  
> neb\_cell\_algo 1 # Generalized Solid-State NEB  
> mep\_solver 0 # Use steepest-descent as diff. equation solver  
> fxcartfactor 0.8 # Scaling factor for the steepest-descent algo  
> nsym 1 # For NEB to work properly  
> nimage 7 # 7 images along the PATH  
> dynimage 0 5\*1 0 # First and last images are fixed  
> ntimimage 10 # Max. number of NEB steps  
> tolimg 5.0e-04 # Tolerance on energy to converge NEB

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<div class="post-metadata">

**Author:** ![sms](https://discourse.abinit.org/letter_avatar_proxy/v4/letter/s/ecb155/32.png) [@sms](https://discourse.abinit.org/u/sms)\
**Post date:** [January 2, 2026, 10:02pm UTC](https://discourse.abinit.org/t/how-to-perform-nudge-elastic-bands-calculation/3791/3 "2026-01-02T22:02:26Z")

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Hi Antonius,

Thanks for your valuable response. I tried some from the available tutorials of parallelism. I faced an error like this -

m\_splines.F90

Fatal Error

I didn’t understand what does it mean and why is this happening. All I changed is a different cell parameters for my crystal structure. The main tutorial worked properly. But if I change these parameters for my structure it fails with the above message.

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<div class="post-metadata">

**Author:** ![Antonius](https://discourse.abinit.org/user_avatar/discourse.abinit.org/antonius/32/888_2.png) [@Antonius](https://discourse.abinit.org/u/Antonius)\
**Post date:** [January 6, 2026, 8:04pm UTC](https://discourse.abinit.org/t/how-to-perform-nudge-elastic-bands-calculation/3791/4 "2026-01-06T20:04:59Z")

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Hi,

You would need provide more information so that we can help you. If you cannot solve your issue, try preparing a minimal working example (MWE) that reproduces the bug, and perhaps another version that doesn’t cause the bug, if that’s what you have.