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- corrected setforce/spin
- added an example
- added the documentation (in setforce)
- updated the Howto_spin documentation
This commit is contained in:
julient31
2019-04-10 13:18:33 -06:00
parent 3d7b387786
commit 70c816aa02
11 changed files with 117 additions and 33 deletions
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23
doc/src/Howto_spins.txt
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@ -10,7 +10,7 @@ Documentation"_ld - "LAMMPS Commands"_lc :c
Magnetic spins :h3
The magnetic spin simulations are enabled by the SPIN package, whose
implementation is detailed in "Tranchida"_#Tranchida7.
implementation is detailed in "Tranchida"_#Tranchida.
The model represents the simulation of atomic magnetic spins coupled
to lattice vibrations. The dynamics of those magnetic spins can be used
@ -36,13 +36,28 @@ A Langevin thermostat can be applied to those magnetic spins using
"fix langevin/spin"_fix_langevin_spin.html. Typically, this thermostat
can be coupled to another Langevin thermostat applied to the atoms
using "fix langevin"_fix_langevin.html in order to simulate
thermostatted spin-lattice system.
thermostatted spin-lattice systems.
The magnetic Gilbert damping can also be applied using "fix
langevin/spin"_fix_langevin_spin.html. It allows to either dissipate
the thermal energy of the Langevin thermostat, or to perform a
relaxation of the magnetic configuration toward an equilibrium state.
The command "fix setforce/spin"_fix_setforce.html allows to set the
components of the magnetic precession vectors (while erasing and
replacing the previsouly computed magnetic precession vectors on
the atom).
This command can be used to freeze the magnetic moment of certain
atoms in the simulation by zeroing their precession vector.
The command "fix nve/spin"_fix_nve_spin.html can be used to
perform a simplectic integration of the combined dynamics of spins
and atomic motions.
The minimization style "min/spin"_min_spin.html can be applied
to the spins to perform a minimization of the spin configuration.
All the computed magnetic properties can be output by two main
commands. The first one is "compute spin"_compute_spin.html, that
enables to evaluate magnetic averaged quantities, such as the total
@ -54,6 +69,6 @@ magnetic spin, or the magnetic force acting on this spin.
:line
:link(Tranchida7)
:link(Tranchida)
[(Tranchida)] Tranchida, Plimpton, Thibaudeau and Thompson,
arXiv preprint arXiv:1801.10233, (2018).
Journal of Computational Physics, 372, 406-425, (2018).

2
doc/src/fix_langevin_spin.txt
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@ -99,4 +99,4 @@ integration fix (e.g. {fix nve/spin}).
:link(Tranchida2)
[(Tranchida)] Tranchida, Plimpton, Thibaudeau and Thompson,
Journal of Computational Physics, (2018).
Journal of Computational Physics, 372, 406-425, (2018).

2
doc/src/fix_nve_spin.txt
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@ -73,4 +73,4 @@ instead of "array" is also valid.
:link(Tranchida1)
[(Tranchida)] Tranchida, Plimpton, Thibaudeau and Thompson,
Journal of Computational Physics, (2018).
Journal of Computational Physics, 372, 406-425, (2018).

20
doc/src/fix_setforce.txt
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@ -8,6 +8,7 @@
fix setforce command :h3
fix setforce/kk command :h3
fix setforce/spin command :h3
[Syntax:]
@ -27,6 +28,7 @@ keyword = {region} :l
fix freeze indenter setforce 0.0 0.0 0.0
fix 2 edge setforce NULL 0.0 0.0
fix 1 edge setforce/spin 0.0 0.0 0.0
fix 2 edge setforce NULL 0.0 v_oscillate :pre
[Description:]
@ -65,6 +67,19 @@ to it.
:line
Style {spin} suffix sets the components of the magnetic precession
vectors instead of the mechanical forces. This also erases all
previously computed magnetic precession vectors on the atom, though
additional magnetic fixes could add new forces.
This command can be used to freeze the magnetic moment of certain
atoms in the simulation by zeroing their precession vector.
All options defined above remain valid, they just apply to the magnetic
precession vectors instead of the forces.
:line
Styles with a {gpu}, {intel}, {kk}, {omp}, or {opt} suffix are
functionally the same as the corresponding style without the suffix.
They have been optimized to run faster, depending on your available
@ -117,7 +132,10 @@ forces to any value besides zero when performing a minimization. Use
the "fix addforce"_fix_addforce.html command if you want to apply a
non-zero force to atoms during a minimization.
[Restrictions:] none
[Restrictions:]
The fix {setforce/spin} only makes sense when LAMMPS was built with the
SPIN package.
[Related commands:]

2
doc/src/pair_spin_dmi.txt
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@ -88,4 +88,4 @@ package"_Build_package.html doc page for more info.
Physical Review B, 88(18), 184422. (2013).
:link(Tranchida5)
[(Tranchida)] Tranchida, Plimpton, Thibaudeau and Thompson,
Journal of Computational Physics, (2018).
Journal of Computational Physics, 372, 406-425, (2018).

2
doc/src/pair_spin_exchange.txt
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@ -95,4 +95,4 @@ package"_Build_package.html doc page for more info.
:link(Tranchida3)
[(Tranchida)] Tranchida, Plimpton, Thibaudeau and Thompson,
Journal of Computational Physics, (2018).
Journal of Computational Physics, 372, 406-425, (2018).

2
doc/src/pair_spin_magelec.txt
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@ -70,4 +70,4 @@ package"_Build_package.html doc page for more info.
:link(Tranchida4)
[(Tranchida)] Tranchida, Plimpton, Thibaudeau, and Thompson,
Journal of Computational Physics, (2018).
Journal of Computational Physics, 372, 406-425, (2018).

2
doc/src/pair_spin_neel.txt
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@ -80,4 +80,4 @@ package"_Build_package.html doc page for more info.
:link(Tranchida6)
[(Tranchida)] Tranchida, Plimpton, Thibaudeau and Thompson,
Journal of Computational Physics, (2018).
Journal of Computational Physics, 372, 406-425, (2018).

59
examples/SPIN/setforce_spin/in.spinmin.setforce Normal file
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@ -0,0 +1,59 @@
units metal
dimension 3
boundary f f f
atom_style spin
# necessary for the serial algorithm (sametag)
atom_modify map array
lattice sc 3.0
region box block 0.0 10.0 0.0 10.0 0.0 1.0
create_box 2 box
region reg1 block 0.0 10.0 0.0 5.0 0.0 1.0
region reg2 block 0.0 10.0 6.0 10.0 0.0 1.0
create_atoms 1 region reg1
create_atoms 2 region reg2
# setting mass, mag. moments, and interactions for bcc iron
mass 1 55.845
mass 2 55.845
set region reg1 spin 2.2 0.0 0.0 1.0
set region reg2 spin/random 31 2.2
group fixed_spin region reg1
pair_style hybrid/overlay spin/exchange 3.1 spin/dmi 3.1
pair_coeff * * spin/exchange exchange 3.1 -0.01593 0.06626915552 1.211
pair_coeff * * spin/dmi dmi 3.1 0.12e-03 0.0 0.0 1.0
neighbor 0.1 bin
neigh_modify every 10 check yes delay 20
fix 1 all precession/spin zeeman 0.0 0.0 0.0 1.0 anisotropy 5e-05 0.0 0.0 1.0
fix_modify 1 energy yes
fix 2 fixed_spin setforce/spin 0.0 0.0 0.0
fix 3 all langevin/spin 0.0 0.1 21
fix 4 all nve/spin lattice no
timestep 0.0001
compute out_mag all spin
variable magx equal c_out_mag[1]
variable magy equal c_out_mag[2]
variable magz equal c_out_mag[3]
variable magnorm equal c_out_mag[4]
variable emag equal c_out_mag[5]
variable tmag equal c_out_mag[6]
thermo 1000
thermo_style custom step time v_magx v_magz v_magnorm v_tmag etotal
thermo_modify format float %20.15g
compute outsp all property/atom spx spy spz sp fmx fmy fmz
dump 1 all custom 1000 dump.lammpstrj type x y z c_outsp[1] c_outsp[2] c_outsp[3] c_outsp[5] c_outsp[6] c_outsp[7]
min_style spin
min_modify alpha_damp 1.0 discrete_factor 20.0
minimize 1.0e-16 1.0e-16 50000 1000

2
src/SPIN/fix_nve_spin.cpp
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@ -475,8 +475,6 @@ void FixNVESpin::ComputeInteractionsSpin(int i)
locksetforcespin->single_setforce_spin(i,fmi);
}
//printf("test after setforce: %g %g %g \n",fmi[0],fmi[1],fmi[2]);
// replace the magnetic force fm[i] by its new value fmi
fm[i][0] = fmi[0];

34
src/SPIN/fix_setforce_spin.cpp
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@ -128,8 +128,6 @@ void FixSetForceSpin::single_setforce_spin(int i, double fmi[3])
int *mask = atom->mask;
int nlocal = atom->nlocal;
//printf("test inside before setforce: %g %g %g \n",fmi[0],fmi[1],fmi[2]);
// update region if necessary
Region *region = NULL;
@ -148,19 +146,18 @@ void FixSetForceSpin::single_setforce_spin(int i, double fmi[3])
foriginal[0] = foriginal[1] = foriginal[2] = 0.0;
force_flag = 0;
// constant force
if (varflag == CONSTANT) {
if (mask[i] & groupbit) {
//if (region && !region->match(x[i][0],x[i][1],x[i][2])) continue;
//if (region && region->match(x[i][0],x[i][1],x[i][2])){
if (region && !region->match(x[i][0],x[i][1],x[i][2])) return;
foriginal[0] += fmi[0];
foriginal[1] += fmi[1];
foriginal[2] += fmi[2];
if (xstyle) fmi[0] = xvalue;
if (ystyle) fmi[1] = yvalue;
if (zstyle) fmi[2] = zvalue;
//printf("test inside inter setforce: %g %g %g \n",fmi[0],fmi[1],fmi[2]);
//}
}
// variable force, wrap with clear/add
@ -182,21 +179,18 @@ void FixSetForceSpin::single_setforce_spin(int i, double fmi[3])
modify->addstep_compute(update->ntimestep + 1);
if (mask[i] & groupbit) {
//if (region && !region->match(x[i][0],x[i][1],x[i][2])) continue;
if (region && region->match(x[i][0],x[i][1],x[i][2])) {
foriginal[0] += fmi[0];
foriginal[1] += fmi[1];
foriginal[2] += fmi[2];
if (xstyle == ATOM) fmi[0] = sforce[i][0];
else if (xstyle) fmi[0] = xvalue;
if (ystyle == ATOM) fmi[1] = sforce[i][1];
else if (ystyle) fmi[1] = yvalue;
if (zstyle == ATOM) fmi[2] = sforce[i][2];
else if (zstyle) fmi[2] = zvalue;
}
if (region && !region->match(x[i][0],x[i][1],x[i][2])) return;
foriginal[0] += fmi[0];
foriginal[1] += fmi[1];
foriginal[2] += fmi[2];
if (xstyle == ATOM) fmi[0] = sforce[i][0];
else if (xstyle) fmi[0] = xvalue;
if (ystyle == ATOM) fmi[1] = sforce[i][1];
else if (ystyle) fmi[1] = yvalue;
if (zstyle == ATOM) fmi[2] = sforce[i][2];
else if (zstyle) fmi[2] = zvalue;
}
}
//printf("test inside after setforce: %g %g %g \n",fmi[0],fmi[1],fmi[2]);
}
/* ---------------------------------------------------------------------- */