这一篇主要参考官网Workshop中Day3(PDF_link)内容,联系制作.ucf文件,以及生成skyrmion结构

input file

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#-----------------------------------------
# Unit Cell
#-----------------------------------------
material:file=Co.mat
material:unit-cell-file = "file.ucf"
#-----------------------------------------
# System Dimensions:
#-----------------------------------------
dimensions:system-size-x = 10.0 !nm
dimensions:system-size-y = 10.0 !nm
dimensions:system-size-z = 2.715 !A
#-----------------------------------------
# Simlation attributes:
#-----------------------------------------
sim:total-time-steps=3000000
sim:equilibration-temperature=30
sim:equilibration-time-steps=10000
sim:time-steps-increment=1
sim:time-step=1e-16

sim:minimum-temperature=0
sim:maximum-temperature=30.0
sim:applied-field-strength=0.0
sim:cooling-time=100!ps
sim:cooling-function=gaussian

#-----------------------------------------
# Program and integrator details
#-----------------------------------------
sim:program=field-cool
sim:integrator=llg-heun

#-----------------------------------------
# data output
#-----------------------------------------
output:output-rate=10000
output:real-time
output:temperature
output:mean-magnetisation-length
output:magnetisation-length
output:magnetisation
output:mean-susceptibility

config:atoms
config:atoms-output-rate=100000

Co.mat file

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#-----------------------------------------
# Number of Materials
#-----------------------------------------
material:num-materials=1
#-----------------------------------------
# Material 1 Cobalt Generic
#-----------------------------------------
material[1]:material-name=Co
material[1]:damping-constant=1.0
material[1]:initial-spin-direction=random
material[1]:atomic-spin-moment=1.72 !muB
material[1]:uniaxial-anisotropy-constant=5e-23

file.ucf file

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#Unit cell size:
2.715 2.715 2.715
#Unit cell vectors:
1 0 0
0 1 0
0 0 1
# Atoms num_atoms, num_materials;id cx cy cz mat cat hcat:
1
0 0 0 0 0 1 0
# Interactions n exctype; IID i j dx dy dz Jxx Jxy Jxz Jyx Jyy Jyz Jzx Jzy Jzz:
4 tensorial
0 0 0 1 0 0 1.6e-22 0 -1.60e-22 0 1.6e-22 0 1.60e-22 0 1.6e-22
1 0 0 0 1 0 1.6e-22 0 0 0 1.6e-22 -1.60e-22 0 1.60e-22 1.6e-22
2 0 0 -1 0 0 1.6e-22 0 1.60e-22 0 1.6e-22 0 -1.60e-22 0 1.6e-22
3 0 0 0 -1 0 1.6e-22 0 0 0 1.6e-22 1.60e-22 0 -1.60e-22 1.6e-22

这样一个体系,我的PC i7-3770的CPU跑了大概10min。

Vdc .xyz 结构

Povray画图

调参数提升自己

Povray 标签与animation

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vi spins.pov

修改其中的Set_Camera_Sky(<0,0,1>)Set_Camera_Sky(<1,0,0>),然后运行

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povray spins

图会从上面的菱形变成正方形(角度不同)。然后制作gif动画:

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convert -delay 10 -loop 0 *.png animation.gif

加磁场Field Cooling

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sim:applied-field-strength=4.0

这是在Day3 幻灯片开始的地方就建议的磁场(单位Tesla)。

结果: