- Jianqiu Huang added an answer:8How does vacancy concentration effect vacancy migration barrier?
- Salman Ahmad Khan added an answer:3Does increasing the number of images improve convergence when doing a NEB calculation using VASP? Any other pointers for improving convergence?
- Hamidreza Simchi added an answer:4Is Rashba SOI or first principle calculation more suitable for a surface system?
- Jamoliddin Razzokov added an answer:2Any advice for simple first principles calculations based on DFT to validate Lithium ion anode performance ?
- Tanmoy Chakraborty added an answer:9Does anyone know how to calculate free energy using quasi-harmonic Debye model using PHONOPY?
- Yin Li added an answer:9How to place molecules whose atomic position are written in Cartesian coordinate system into unit cell using material studio software?
- Yin Li added an answer:13How to define a crystal structure in quantum-espresso (pwscf)?
- Darshana Wickramaratne added an answer:4Can anyone help with the following issues about hse06 hybrid functional calculations using vasp 5.3.5?
- V. V. Bannikov added an answer:2What are the effects of high electron density at the fermi level regarding the oxygen reduction reaction?
- Sayyed Faramarz Tayyari added an answer:5How to properly apply Gaussian G2 method?
- Jian Hui Lan added an answer:8How do you calculate the energy of a gas phase oxygen molecule in its triplet ground state?
- Ahmad Bahmani added an answer:7How can I find out the atomic position of a crystal with known space group(using http://www.cryst.ehu.es/ website)?
- Andrij Vasylenko added an answer:6How to find Cartesian atomic coordinates of Silicon in a unit cell on a surface?
- Giuseppe Pintaude added an answer:11How could hardness of metals or alloys be quantified or measured theoretically?
- Larraga-Gutierrez Manuel Jose added an answer:9What is the good software for nonlinear curve fitting rather than Excel and Origin?
- Zeyad Adnan Saleh added an answer:3What type of analysis we can do to except band gap measurement using UV-visible spectroscopy?
- Waheed Adeniyi Adeagbo added an answer:6How can I calculate the defect formation energy by DFT?
- David Foster added an answer:2How to find mobility of a particular system using VASP?
- Kingsley Onyebuchi Obodo added an answer:6How can I calculate the guarantee of accuracy from the plane wave basis kinetic energy cutoff, Monkhorst-Pack mesh and Supercells atoms number?
- Shuai Zhao added an answer:2Is the K-points path the same as the primary cell for a superlattice?
- Danny E. P. Vanpoucke added an answer:3Can you help me with VASP calculation of elastic moduli for hybrid functional (HSE,PBE0)?
- Viorel Chihaia added an answer:3How to keep slab layers constant in Lammps?
- Zol Bahri Razali added an answer:1What is the surface of a three component system for the transformation from liquid to solid state of matter?
- Niyaz Safarov added an answer:4What is the best program to make beautiful 3D atomic figures?
- Ihosvany Camps added an answer:6How can I find the k-points for band structure calculation?
- Danylo Zherebetskyy added an answer:4How to find the Band structure of a material using VASP?
- Peram sreenivasa Reddy asked a question:OpenHow do you install KKR-ASA code and how do you run the examples?
- Krisztián Palotás added an answer:2What is CPA-EMTO code?
- Dipayan Sen added an answer:3Is UFF (Universal Force Field) potential a good choice for modelling metal clusters?
- Marcin Andrzejak added an answer:1How to confirm that my band gap is correct in the absence of experimental results?

Using VASP I calculated the activation barrier of vacancy diffusion on the surface of ZnO for a 2x2 3 layered cell, where i had removed 1 oxygen atom out of 4 on the surface, and it came out to be 1.35eV and then I calculated the migration barrier for a 3x3 3 layered cell, where I had removed 1 out of the 9 oxygen atoms on the surface, the barrier came out to be 1.67 eV.

The thing which is bugging me is, why is the barrier higher at a lower vacancy concentration. Is there an explanation for this? I was wondering if i should use a similar sized cell for both the calculations ( a 6x6 cell)? The only thing that is different in the two calculations are the KPOINTS. For the 2x2 cell I have used a 2x3x1 mesh and for the 3x3 cell I have used a 1x2x1 mesh.