Hello everyone,


I am using the DFT+U approach to compare my system with experimental results. 
To do so, I want to optimize the effective on-site Coulomb value (U) and keep 
the exchange value (J) fixed while simultaneously relaxing the structure using 
vc-relax. When I try and submit the vc-relax (or even relax) calculations, I 
get the following error:

?%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
? ? ?Error in routine force_hub (1):
? ? ? forces in full LDA+U scheme are not yet implemented
?%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

This doesn't seem right to me. Is it true what the error says, that the force 
calculations are not yet implemented in the "rotationally invariant scheme of 
Liechtenstein et. Al., using Hubbard_U and Hubbard_J"? Perhaps I have made a 
mistake in my input file. The system portion of my input file is given:

&SYSTEM
? ? ibrav ? ? ? ? ? ?= 0
? ? celldm(1) ? ? ? ?= 1.889725989
? ? nat ? ? ? ? ? ? ?= 73
? ? ntyp ? ? ? ? ? ? = 4
? ? ecutwfc ? ? ? ? ?= 60
? ? ecutrho ? ? ? ? ?= 600
? ? occupations ? ? ?= 'smearing'
? ? degauss ? ? ? ? ?= 0.001
? ? nspin ? ? ? ? ? ?= 2
? ? starting_magnetization(1) = 0.5
? ? starting_magnetization(2) =-0.5
? ? tot_magnetization= 0.0
? ? lda_plus_u ? ? ? = .t.
? ? lda_plus_u_kind ?= 1
? ? Hubbard_U(1) ? ? = 2.6
? ? Hubbard_U(2) ? ? = 2.6
? ? Hubbard_J0(1) ? ?= 1.2
? ? Hubbard_J0(2) ? ?= 1.2
/

NOTE: Whenever lda_plus_u_kind is set to 1, any relax calculation gives the 
above error. When it is 0, it runs fine.

Is it necessary to include "lda_plus_u_kind = 1" parameter or will the code 
still incorporate U and J if I set it to 0 (simplified version of Cococcioni 
and de Gironcoli using Hubbard_U)?

Thanks in advance.

--
Izaak Williamson
Graduate Student
Department of Materials Science and Engineering
Boise State University
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