Dear VASPers;
I am having problems relaxing Rhodium four tetrahedron on Ceria.
What does a positive external pressure and an apparently unstable minimum represent.
The calculation finishes but the structure is unusually unstable; other metals are fine.
------------------------ aborting loop because EDIFF is reached ----------------------------------------
FREE ENERGIE OF THE ION-ELECTRON SYSTEM (eV)
---------------------------------------------------
free energy TOTEN = -1423.585005 eV
energy without entropy= -1423.807009 energy(sigma->0) = -1423.659006
CHARGE: cpu time 50.24: real time 50.25
FORLOC: cpu time 2.17: real time 2.17
FORNL : cpu time 158.03: real time 158.10
STRESS: cpu time 428.43: real time 428.62
FORCOR: cpu time 4.66: real time 4.67
FORHAR: cpu time 3.38: real time 3.38
FORCE on cell =-STRESS in cart. coord. units (eV):
Direction XX YY ZZ XY YZ ZX
--------------------------------------------------------------------------------------
Alpha Z 3000.83565 3000.83565 3000.83565
Ewald 642281.57760642990.06788************ 232.63429 -320.44786 173.59526
Hartree674030.11757674424.80380************ 130.66935 -241.65554 86.02032
E(xc) -5256.45473 -5254.40578 -5265.63471 0.42441 0.18255 0.19365
Local ************************************ -343.02991 588.87695 -256.27557
n-local 390.34453 398.33348 412.55188 2.55269 2.48099 2.08381
augment -102.05578 -113.05767 -96.38722 -3.77686 -2.48162 -1.73639
Kinetic 22836.76058 22798.25324 22812.68923 -10.14320 -7.03218 -3.88506
Fock 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000
-------------------------------------------------------------------------------------
Total 901.38601 944.85527 1207.42773 9.33078 19.92329 -0.00398
in kB 372.62467 390.59446 499.13950 3.85726 8.23611 -0.00164
external pressure = 420.79 kB Pullay stress = 0.00 kB
<span class='smallblacktext'>[ Edited ]</span>
supported clusters and external pressure
Moderators: Global Moderator, Moderator
-
- Newbie
- Posts: 24
- Joined: Wed Feb 17, 2010 11:34 pm
- License Nr.: 1118
supported clusters and external pressure
Last edited by Sonny on Tue Dec 28, 2010 11:26 am, edited 1 time in total.
-
- Administrator
- Posts: 2921
- Joined: Tue Aug 03, 2004 8:18 am
- License Nr.: 458
supported clusters and external pressure
positive pressure says that the volume as set in POSCAR is to small
BUT
sorry one cannot give an answer based on the data you show. Do you have a Ceria slab with Rh adsorbate? please note that it makes no sense to evaluate the pressure on a unit cell which contains vacuum
are all ionic steps of your calculation fully converged electronically?
what do you mean by 'unusually unstable' ?
BUT
sorry one cannot give an answer based on the data you show. Do you have a Ceria slab with Rh adsorbate? please note that it makes no sense to evaluate the pressure on a unit cell which contains vacuum
are all ionic steps of your calculation fully converged electronically?
what do you mean by 'unusually unstable' ?
Last edited by admin on Thu Dec 30, 2010 12:08 pm, edited 1 time in total.
-
- Newbie
- Posts: 24
- Joined: Wed Feb 17, 2010 11:34 pm
- License Nr.: 1118
supported clusters and external pressure
The lattice constant is optimised: I cant see how the volume is too small.
I have a ceria slab with Rh4 tetrahedron adsorbate.
There is vacuum of 15 angstroms from top Rh.
I find the external pressure is consistently negative and small with other metals.
I say unusually unstable as it converges to a structure physically impossible.
the Rh4 configuration relaxes into a standing Rhombus like structure at about 50 degrees.
I am having difficulty with Rh10 also the top atom is unstable (not fully bound) and mixed Rh , Pd clusters of ten atom with Rh at the vertices; the top Rh sinks this time.
I found a recent experimental to help explain the phenomenon as due to metal donation to f states forming heavy electrons. (the interface is reduced)
http://www.sciencedaily.com/releases/20 ... 131342.htm
At this stage I am not able to examine the bandstructure as I would like too.
I gather Rh nanostructures are quite remarkable in their degeneracy and magetism.
We also have other HRTEM evidence of odd 110 Rh surface of Rh,Pd nanoclusters (~40 atoms) on Cerium dioxide powder, XAFS also lends some insight into amorphous Rhodium phase here.
<span class='smallblacktext'>[ Edited Mon Jan 17 2011, 02:13AM ]</span>
I have a ceria slab with Rh4 tetrahedron adsorbate.
There is vacuum of 15 angstroms from top Rh.
I find the external pressure is consistently negative and small with other metals.
I say unusually unstable as it converges to a structure physically impossible.
the Rh4 configuration relaxes into a standing Rhombus like structure at about 50 degrees.
I am having difficulty with Rh10 also the top atom is unstable (not fully bound) and mixed Rh , Pd clusters of ten atom with Rh at the vertices; the top Rh sinks this time.
I found a recent experimental to help explain the phenomenon as due to metal donation to f states forming heavy electrons. (the interface is reduced)
http://www.sciencedaily.com/releases/20 ... 131342.htm
At this stage I am not able to examine the bandstructure as I would like too.
I gather Rh nanostructures are quite remarkable in their degeneracy and magetism.
We also have other HRTEM evidence of odd 110 Rh surface of Rh,Pd nanoclusters (~40 atoms) on Cerium dioxide powder, XAFS also lends some insight into amorphous Rhodium phase here.
<span class='smallblacktext'>[ Edited Mon Jan 17 2011, 02:13AM ]</span>
Last edited by Sonny on Wed Jan 05, 2011 8:08 pm, edited 1 time in total.