使用DFTB进行片段轨道作用分析、转移积分

与ADF、BAND基于DFT的EDA分析，在使用上基本上没有差别，但DFTB目前不输出能量分解分析的数据，只是产生整体轨道与片段轨道关系的信息。

这里选择了精度最高的DFTB3方法，并结合D4色散修正。 将两个区域分别设置为两个Region： 勾选片段功能即打开EDA：

保存并提交作业。

如果用户需要计算转移积分，则只需要在生成的*.run文件中加一行：

            TransferIntegrals Yes

类似如下：

Engine DFTB
    Model DFTB3
    ResourcesDir DFTB.org/3ob-3-1
    DispersionCorrection D4
    Properties
        Fragments
            TransferIntegrals Yes
            File Region_1.rkf
            File Region_2.rkf
        End
    End
EndEngine
eor

在SCM → Level中，类似DFT一样，可以看到整体能级与碎片能级的关系，以及轨道组分比例：

如果计算了转移积分，则可以看到类似如下数据：

 Charge transfer integrals relevant for hole or electron mobility calculations

  
 Electronic coupling V (also known as effective (generalized) transfer integrals J_eff)
 V = (J-S(e1+e2)/2)/(1-S^2)
 For electron mobility calculations the fragment LUMO’s are considered.
 For hole mobility calculations the fragment HOMO’s are considered.
 Couplings are printed also for (near) degenerate fragment orbitals within  0.100     eV of fragment HOMO or LUMO.
 This threshold for treating fragment MOs as degenerate can be set by the Properties%Fragments%TIDegeneracyThreshold key.

 e1(hole) Site energy HOMO fragment 1:                                        -6.85930 eV
 e2(hole) Site energy HOMO fragment 2:                                        -9.49471 eV
 J(hole) Charge transfer integral HOMO fragment 1 - HOMO fragment 2:          -0.06069 eV
 S(hole) Overlap integral HOMO fragment 1 - HOMO fragment 2:                   0.00160
 V for hole transfer:                                                         -0.04764 eV

 e1(electron) Site energy LUMO fragment 1:                                        12.47221 eV
 e2(electron) Site energy LUMO fragment 2:                                         9.83354 eV
 J(electron) Charge transfer integral LUMO fragment 1 - LUMO fragment 2:          -0.15979 eV
 S(electron) Overlap integral LUMO fragment 1 - LUMO fragment 2:                   0.00543
 V for electron transfer:                                                         -0.22041 eV

 e1 Site energy HOMO fragment 1:                                                              -6.85930 eV
 e2 Site energy LUMO fragment 2:                                                               9.83354 eV
 S(Charge_Recombination) Overlap integral HOMO fragment 1 - LUMO fragment 2:                   0.00403
 J(Charge_Recombination) Charge transfer integral HOMO fragment 1 - LUMO fragment 2:          -0.13581 eV
 V for charge_recombination 1-2:                                                              -0.14181 eV

 e1 Site energy LUMO fragment 1:                                                              12.47221 eV
 e2 Site energy HOMO fragment 2:                                                              -9.49471 eV
 J(Charge_Recombination) Charge transfer integral LUMO fragment 1 - HOMO fragment 2:           0.22890 eV
 S(Charge_Recombination) Overlap integral LUMO fragment 1 - HOMO fragment 2:                  -0.00448
 V for charge_recombination 2-1:                                                               0.23557 eV

 Electronic coupling V (summed over printed couplings)
 Square root of (sum of squares of printed V's):
 -----------------------------------------------------

 V for hole transfer:                    0.04764 eV
 V for electron transfer:                0.22041 eV
 V for charge_recombination 1-2:         0.14181 eV
 V for charge_recombination 2-1:         0.23557 eV

输出格式与ADF是一致的。