Notes of gaussian

本教程基于 HPC of zhenggroup 集群环境

参考资料 http://sobereva.com/list.html

零、理论基础

泛函/基组设置

简谈量子化学计算中DFT泛函的选择
 谈谈量子化学中基组的选择

激发态

乱谈激发态的计算方法
 Gaussian中用TDDFT计算激发态和吸收、荧光、磷光光谱的方法
 电子激发任务中轨道跃迁贡献的计算

一、输入文件

input.gjf

%mem=84GB
%nprocshared=48
%chk=COF-3-td.chk
#p PBE1PBE scrf=(smd,solvent=water) def2TZVP em=GD3BJ TD(nstates=10) IOp(9/40=4)

COF-3

0 1
 C                 33.03196170  -14.12931527    1.88576471
 H                 31.92769914  -14.10953751    2.72772983
 O                 30.78605907  -13.40639889    2.39344442
 N                 30.71722291  -12.70823752    1.19042342
...

二、输出文件

chk → fchk
/public/software/g16/formchk filename

HOMO-LUMO gap

理论基础

正确地认识分子的能隙(gap)、HOMO和LUMO
(计算DFT, 虚拟态，轨道没有真实存在)
HOMO-LUMO gap = E(LUMO) - E(HOMO) > 0
(UV-Vis：波长最大的吸收峰位置; TDDFT，真实态，电子态真实存在)
Optical gap: 基态电子态通过吸收光子所能跃迁到的最低激发态对应的激发能，S0态极小点结构下S0到S1态的垂直跃迁对应的激发能。

HOMO-LUMO gap越小，一般认为导电性越好。
HOMO-LUMO gap越小，通常极化率也越大

三、结果分析

Excitation、S/D、Visualization

Excitation

Multiwfn
input.out (out文件路径)
18-Electron excitation analysis
15-Print major MO transitions in all excited states

S/D

Multiwfn
COF-3-td.fchk (fchk文件路径)
18-Electron excitation analysis
1-Analyze and visualize hole&electron distribution, transition density, and transition electric/magnetic dipole moment density
input.out (out文件路径)
S0→S？
1-Visualize and analyze hole, electron, transition density and so on
2-Medium quality grid, covering whole system, about 512000 points in total
Sm index/D index
3-Show isosurface of hole and electron distribution simultaneously
7-Show isosurface of charge density difference

Visualization

https://www.bilibili.com/video/BV1B94y1J7gR/?spm_id_from=333.788&vd_source=dbd7edddb514b6a82b44048682e9c391
cube 文件生成 + VMD可视化

文献引用

[1] def2-TZVP基组 https://doi.org/10.1063/1.467146
[2] Multiwfn https://doi.org/10.1002/jcc.22885
[3] 溶剂模型 https://doi.org/10.1063/1.3359469
[4] xtb https://doi.org/10.1021/acs.jctc.8b01176
[5] D3BJ https://doi.org/10.1002/jcc.21759