Dielectric Constant and Surface Relaxation

Message

juwono · #1 Post by **juwono** » Mon Jul 03, 2006 9:42 pm

Hi All,

I am a new VASP-er and I have some difficulties running the program.

I want to do metal in implicit water simulation by changing the dielectric constant of the vacum from E=1 to some other values. But I couldn't found any way to do that in the VASP manual.

I am also running 7 layers of metal and I want to find a way to relax the top layer of the metal layers in Z-direction but keeping the layer flat, that is the Z coordinates of the top atoms will always have the same Z coordinate relative to each other.

Thank you very much for your help.
tjipto

tjf · #2 Post by **tjf** » Tue Jul 04, 2006 9:42 am

[quote="juwono"]I am also running 7 layers of metal and I want to find a way to relax the top layer of the metal layers in Z-direction but keeping the layer flat, that is the Z coordinates of the top atoms will always have the same Z coordinate relative to each other. [/quote]

That kind of constrained optimisation is missing from VASP (though I recall hearing rumours of someone hacking up a routine to slot in). You can manually simulate it, doing energy calculations scanning the Z coordinate for that layer.

juwono · #3 Post by **juwono** » Tue Jul 04, 2006 2:03 pm

Thanks for the reply.
I think I am going to average the last z coordinate of the optimisation, and scan the Z coordinate around that average value.

#4 Post by **admin** » Tue Jul 11, 2006 8:23 am

1) the dielectric constant cannot be changed from 1 in vasp.4.6
2) yes constrained relaxations have to be done 'by hand'