AI摘要:Lammps has updated a new command "fix qtpie/reaxff" in its latest version, which may solve some issues with "fix qeq/reaxff" in charge balance. The usage is similar, but requires an "exp.qtpie" file with data from Chen's 2009 thesis.
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昨天晚上无意间发现了一个新命令fix qtpie/reaxff
,lammps_19Nov2024
版本刚刚更新的。看起来能解决fix qeq/reaxff
在电荷平衡时遇到的一些问题?
https://docs.lammps.org/fix_qtpie_reaxff.html
具体结果还没有对比过。使用上就是将
fix rqeq all qeq/reaxff 1 0.0 10.0 1.0e-6 reaxff
改为
fix rqeq all qtpie/reaxff 1 0.0 10.0 1.0e-6 reaxff exp.qtpie
其中exp.qtpie文件中的数据可以由[Chen 2009:Theory and applications of fluctuating-charge models]博士论文 Table 2.2 获得。
Element | Slater exponent | Gaussian exponent | Error |
---|---|---|---|
H | 1.0698 | 0.5434 | 0.01696 |
Li | 0.4174 | 0.1668 | 0.00148 |
C | 0.8563 | 0.2069 | 0.00162 |
N | 0.9089 | 0.2214 | 0.00166 |
O | 0.9745 | 0.2240 | 0.00167 |
F | 0.9206 | 0.2313 | 0.00169 |
Na | 0.4364 | 0.0959 | 0.00085 |
Si | 0.7737 | 0.1052 | 0.00088 |
P | 0.8257 | 0.1085 | 0.00089 |
S | 0.8690 | 0.1156 | 0.00092 |
Cl | 0.9154 | 0.1137 | 0.00091 |
K | 0.4524 | 0.0602 | 0.00125 |
Br | 1.0253 | 0.0701 | 0.00133 |
Rb | 0.5162 | 0.0420 | 0.00121 |
I | 1.0726 | 0.0686 | 0.00127 |
Cs | 0.5663 | 0.0307 | 0.00114 |
比如对于C、Si、O三种原子,exp.qtpie如下(#是注释):
# An example gfile. Exponents are taken from Table 2.2 of Chen, J. (2009).
# Theory and applications of fluctuating-charge models.
# The units of the exponents are 1 / (Bohr radius)^2 .
1 0.2069 # C
2 0.1052 # Si
3 0.2240 # O
当然,要安装最新的lammps19Nov2024
版本。