使用CDFT方法限制局部带电
软件版本为AMS2019.3及之前的版本，AMS2020以后的版本请参考链接：Constrained DFT（CDFT）方法限制局部带电
以如下两个分子之间相互作用为例，其中$CO_2$带-1电荷，大分子带+1电荷，总体为中性。当然其他带电情况也是可以的，但是CDFT相关设置目前只允许设置一个限制条件。本例中，总电荷在Main中设置完毕，对$CO_2$带电条件的设置在CDFT面板完成。
参数设置
Main面板一般性参数设置，包括总电荷、基组、泛函等，需要注意的是，因为两个片段实际都是开壳层因此选择了Unrestricted方法。基组需要选择Core None，因为本方法不支持Frozen core。
设置分区：
选择限制条件为charge，表示只限制电荷，当然选择charge and spin同时限制电荷、自旋。并设置某个分区的电荷，本例设置$CO_2$电荷量为-1
计算过程，我们可以看到logfile中，存在两个片段之间的自洽迭代的过程：
Jul15-2020> <17:59:02> >>>> CORORT <Jul15-2020> <17:59:02> >>>> CLSMAT <Jul15-2020> <17:59:02> >>>> ORTHON <Jul15-2020> <17:59:02> >>>> GENPT <Jul15-2020> <17:59:02> Block Length= 128 <Jul15-2020> <17:59:02> >>>> PTBAS <Jul15-2020> <17:59:04> >>>> CYCLE <Jul15-2020> <17:59:08> Spin 1Set 1Initial Constraints: 0.11500000000000E+02 <Jul15-2020> <17:59:08> Spin 2Set 1Initial Constraints: 0.11500000000000E+02 <Jul15-2020> <17:59:08> ==> CDFT: constraining charge only <Jul15-2020> <17:59:08> ==> New CDFT calculation <Jul15-2020> <17:59:09> |Error| MaxErr Wt(A-DIIS) <Jul15-2020> <17:59:09> 1 12.08432412 0.69447419 <Jul15-2020> <17:59:13> 2 1.94388440 0.12393508 100.0 <Jul15-2020> <17:59:14> CDFT converged in 44 iterations <Jul15-2020> <17:59:17> 3 0.92925582 0.07717285 100.0 <Jul15-2020> <17:59:19> CDFT converged in 42 iterations <Jul15-2020> <17:59:22> 4 1.25040843 0.10040657 100.0 <Jul15-2020> <17:59:24> CDFT converged in 32 iterations <Jul15-2020> <17:59:27> 5 0.50153097 0.03730934 36.7 <Jul15-2020> <17:59:28> CDFT converged in 40 iterations <Jul15-2020> <17:59:32> 6 0.74086752 0.05969209 100.0 <Jul15-2020> <17:59:33> CDFT converged in 31 iterations <Jul15-2020> <17:59:36> 7 0.58744094 0.03926156 100.0 <Jul15-2020> <17:59:37> CDFT converged in 33 iterations <Jul15-2020> <17:59:40> 8 0.14618167 0.01428787 13.4 <Jul15-2020> <17:59:41> CDFT converged in 27 iterations <Jul15-2020> <17:59:44> 9 0.15237075 0.01669448 13.4 <Jul15-2020> <17:59:45> CDFT converged in 23 iterations <Jul15-2020> <17:59:48> 10 0.04846370 0.00322339 2.2 <Jul15-2020> <17:59:49> CDFT converged in 26 iterations <Jul15-2020> <17:59:52> 11 0.01277386 0.00088450 0.0 <Jul15-2020> <17:59:54> CDFT converged in 38 iterations <Jul15-2020> <17:59:57> 12 0.00701702 0.00052408 0.0 <Jul15-2020> <17:59:58> CDFT converged in 29 iterations <Jul15-2020> <18:00:01> 13 0.00542413 0.00042540 0.0 <Jul15-2020> <18:00:03> CDFT converged in 36 iterations <Jul15-2020> <18:00:06> 14 0.00311121 0.00027062 0.0 <Jul15-2020> <18:00:07> CDFT converged in 23 iterations <Jul15-2020> <18:00:10> 15 0.00127281 0.00008939 0.0 <Jul15-2020> <18:00:11> CDFT converged in 25 iterations <Jul15-2020> <18:00:14> 16 0.00032242 0.00002445 0.0 <Jul15-2020> <18:00:15> CDFT converged in 24 iterations <Jul15-2020> <18:00:18> 17 0.00022234 0.00002390 0.0 <Jul15-2020> <18:00:19> CDFT converged in 23 iterations <Jul15-2020> <18:00:22> 18 0.00007651 0.00000564 0.0 <Jul15-2020> <18:00:23> CDFT converged in 23 iterations <Jul15-2020> <18:00:25> 19 0.00006136 0.00000541 0.0 <Jul15-2020> <18:00:26> CDFT converged in 24 iterations <Jul15-2020> <18:00:29> 20 0.00010297 0.00000960 0.0 <Jul15-2020> <18:00:30> CDFT converged in 20 iterations <Jul15-2020> <18:00:33> 21 0.00006008 0.00000479 0.0 <Jul15-2020> <18:00:34> CDFT converged in 27 iterations <Jul15-2020> <18:00:37> 22 0.00001474 0.00000108 0.0 <Jul15-2020> <18:00:39> CDFT converged in 33 iterations <Jul15-2020> <18:00:42> 23 0.00000475 0.00000042 0.0 <Jul15-2020> <18:00:43> CDFT converged in 27 iterations <Jul15-2020> <18:00:44> SCF converged <Jul15-2020> <18:00:46> 24 0.00000923 0.00000077 0.0 <Jul15-2020> <18:00:47> CDFT converged in 18 iterations <Jul15-2020> <18:00:49> >>>> TOTEN <Jul15-2020> <18:00:55> >>>> POPAN <Jul15-2020> <18:00:55> >>>> DEBYE <Jul15-2020> <18:00:55> >>>> AMETS <Jul15-2020> <18:00:55> Bond Energy -8.94002996 a.u. <Jul15-2020> <18:00:55> Bond Energy -243.27059290 eV <Jul15-2020> <18:00:55> Bond Energy -5609.95 kcal/mol <Jul15-2020> <18:00:55> >>>> POPUL <Jul15-2020> <18:00:56> NORMAL TERMINATION
结果检查
SCM → View → Properties → Atom info → Mulliken charge → Show：
可以看到$CO_2$区域的总电荷量为-1.类似SCM → Level可以查看能级，与一般分子计算没有没有差别。