adf:ir2019
如何计算分子的频率、红外、零点能、转动能量、转动惯量、熵、焓、热熔与Gibbs自由能
本教程针对AMS2019.3及之前的版本，AMS2020以后的版本请参考链接:气相分子的频率、红外IR、零点能、转动能量、转动惯量、熵、焓、热容与Gibbs自由能，液相自由能与焓的计算
1，优化分子结构
2，导入优化好的坐标到ADFinput中，并设置参数如下图
关于热力学性质的计算参数如下：第一个参数为压强，第二、三个参数是关心的温度范围，例如这里希望关心298.15K、299.15K……398.15K总共101个温度的热力学性质，因此设置参数如下：
3，保存、运行
4，结果查看
在该任何相关的任何窗口，或在ADFjobs中选中该任务之后，点击ADF LOGO > Spectra，即显示振动频率：
如果有虚频，则虚频的峰为负数，此例中没有虚频。点击峰的位置，或者下方列表中计算得到的三个峰的三行，则显示该峰对应的振动模式的振动动画。
点击SCM > Output > Other Properties > Zero-Point Energy可以看到零点能。
在ADF logo > Output >Other properties > Intensities Collected，可以看到文本形式的输出内容，包括强度和热力学信息：
Statistical Thermal Analysis *** ideal gas assumed ***
Pressure: 1.000000 atm.
Lowest Temperature: 298.150000 K
Highest Temperature: 398.150000 K
Nr. of T-steps: 101
Moments of Inertia [amu*bohr^2] and principal axis
==================================================
1.9638 4.4225 6.3862
------------------------------------------------
0.0000 0.0000 1.0000
1.0000 0.0000 0.0000
0.0000 1.0000 0.0000
The rotational contribution to the molecular entropy includes
a term, dependent on the symmetry number sigma. The results
reported below were computed using sigma = 2, determined from
the point group symmetry of the input geometry (C(2V)).
If this is not the correct symmetry, try symmetrizing the molecule before
running the calculation (note: linear molecules should be aligned along one
of the Cartesian axes).
Contributions from frequencies below 20 1/cm are not included in
the vibrational sums. Their contributions, if any, are reported separately.
Temp Transl Rotat Vibrat Total
---- ------ ----- ------ -----
298.15 Entropy (cal/mole-K): 34.608 10.415 0.015 45.039
Internal Energy (Kcal/mole): 0.889 0.889 13.316 15.094
Constant Volume Heat Capacity (cal/mole-K): 2.981 2.981 0.092 6.054
Summary of energy terms
hartree eV kcal/mol kJ/mol
-------------------- ----------- ---------- -----------
Bond Energy: -0.514027806778452 -13.9874 -322.56 -1349.58
Internal Energy: 0.024053624667862 0.6545 15.09 63.15
pV/n = RT: 0.000944186013486 0.0257 0.59 2.48
Enthalpy H: -0.489029996097105 -13.3072 -306.87 -1283.95
-T*S: -0.021399475096437 -0.5823 -13.43 -56.18
Gibbs free energy: -0.510429471193542 -13.8895 -320.30 -1340.13
Temp Transl Rotat Vibrat Total
---- ------ ----- ------ -----
299.14 Entropy (cal/mole-K): 34.625 10.425 0.015 45.066
Internal Energy (Kcal/mole): 0.892 0.892 13.317 15.100
Constant Volume Heat Capacity (cal/mole-K): 2.981 2.981 0.094 6.055
Summary of energy terms
hartree eV kcal/mol kJ/mol
-------------------- ----------- ---------- -----------
Bond Energy: -0.514027806778452 -13.9874 -322.56 -1349.58
Internal Energy: 0.024063177770665 0.6548 15.10 63.18
pV/n = RT: 0.000947321474284 0.0258 0.59 2.49
Enthalpy H: -0.489017307533503 -13.3068 -306.86 -1283.91
-T*S: -0.021483248259844 -0.5846 -13.48 -56.40
Gibbs free energy: -0.510500555793348 -13.8914 -320.34 -1340.32
…………
…………
Temp Transl Rotat Vibrat Total
---- ------ ----- ------ -----
398.15 Entropy (cal/mole-K): 36.045 11.278 0.068 47.391
Internal Energy (Kcal/mole): 1.187 1.187 13.335 15.709
Constant Volume Heat Capacity (cal/mole-K): 2.981 2.981 0.299 6.261
Summary of energy terms
hartree eV kcal/mol kJ/mol
-------------------- ----------- ---------- -----------
Bond Energy: -0.514027806778452 -13.9874 -322.56 -1349.58
Internal Energy: 0.025033642777425 0.6812 15.71 65.73
pV/n = RT: 0.001260867554148 0.0343 0.79 3.31
Enthalpy H: -0.487733296446879 -13.2719 -306.06 -1280.54
-T*S: -0.030069226500753 -0.8182 -18.87 -78.95
Gibbs free energy: -0.517802522947632 -14.0901 -324.93 -1359.49
其中，
- 如同输出文件内容所说，这种计算Gibbs自由能的方式，引入了理想气体近似，
- 转动能级的计算：Moments of Inertia，转动惯量I，在前面有列出。转动能级Erotate=h2*J(J+1)/8π2I，其中J为转动量子数也就是能级序号，I为转动惯量（非负整数），h为普朗克常数（h=6.62606896×10-34J·s），π＝3.141593。
- Transl，Rotat，Vibrat，Total三项列出了各个温度时，熵、内能、热容的平移、转动、振动分量与总和。
- Summary of energy terms，列出了内能、焓、Gibbs自由能等信息。
adf/ir2019.txt · 最后更改: 2022/10/31 19:07 由 liu.jun