The abnormal and negative NEB energy profile
Posted: Sat Dec 02, 2017 9:09 am
Deal all,
I obtained an abnormal and negative energy profile of the phase transition from beta-Ti to alpha-Ti. In general, there is no energy barrier for this phases transitions. However, the flat and descend energy profile may be changed when some additive elements are added.
I want to obtain the flat and descend profile energy profiles of these phase transitions without any additive element. In following figure, the ‘neb-no-CI’ line is the much negative energy profile of the transition using no-climbing-image NEB method, while the ‘imgs-scf’ line is the the static energy of each images. It can be noted that the neb-no-CI line is very strange because the alpha-Ti is most stable Ti (only omega-Ti is slightly lower in energy than alpha-Ti at 0 K). Though I don’t know the precise transition profile, I think it may be as like as the imgs-scf line.
I tried different Optimizer methods, but all the obtained profiles are negative. I relaxed the atom positions of image 4 and 5 after the NEB calculation, as shown the blue triangle, since they are very lower in NEB energy profile. However, it can be seen that the relaxed image 4 and 5 are higher in energy than the alpha-Ti (image 9) and very different from the result of NEB. So what’s the problem of the negative NEB profile? How can I obtain the reasonable NEB profile of this phase transition.
The required input files are compressed and uploaded as 'no-CI.7Z'. Thanks a lot!
I obtained an abnormal and negative energy profile of the phase transition from beta-Ti to alpha-Ti. In general, there is no energy barrier for this phases transitions. However, the flat and descend energy profile may be changed when some additive elements are added.
I want to obtain the flat and descend profile energy profiles of these phase transitions without any additive element. In following figure, the ‘neb-no-CI’ line is the much negative energy profile of the transition using no-climbing-image NEB method, while the ‘imgs-scf’ line is the the static energy of each images. It can be noted that the neb-no-CI line is very strange because the alpha-Ti is most stable Ti (only omega-Ti is slightly lower in energy than alpha-Ti at 0 K). Though I don’t know the precise transition profile, I think it may be as like as the imgs-scf line.
I tried different Optimizer methods, but all the obtained profiles are negative. I relaxed the atom positions of image 4 and 5 after the NEB calculation, as shown the blue triangle, since they are very lower in NEB energy profile. However, it can be seen that the relaxed image 4 and 5 are higher in energy than the alpha-Ti (image 9) and very different from the result of NEB. So what’s the problem of the negative NEB profile? How can I obtain the reasonable NEB profile of this phase transition.
The required input files are compressed and uploaded as 'no-CI.7Z'. Thanks a lot!