HyperChem 7.5

RM1 in HyperChem 7.5

For the earlier 7.5 version of HyperChem, you can still easily run RM1 by simply replacing the AM1 parameters in Hyperchem with the RM1 ones.

If you are an experienced user and if you agree with the disclaimer and conditions below, do the following very carefully:

  1. Find the folder C:\Hyper75\Runfiles.
    C:\Hyper75\ is the default installation folder. If you installed Hyperchem in a different folder, please find it now.
  2. In this folder, you will find the files Am1_1.abpAm1_2.abp, and Am1_3.abp. These files contain the AM1 parameters.
  3. Rename the existing Am1_1.abp to Am1_1.abp_am1; Am1_2.abp to Am1_2.abp_am1; and Am1_3.abp to Am1_3.abp_am1; and leave them there.
  4. Download RM1_Hyper75.zip which contains the files Am1_1.abp_rm1Am1_2.abp_rm1, and Am1_3.abp_rm1, and extract these three files to the directory found in the step 2 above. These files contain the RM1 parameters.
  5. Rename Am1_1.abp_rm1 to Am1_1.abp; Am1_2.abp_rm1 to Am1_2.abp; and Am1_3.abp_rm1 to Am1_3.abp.
  6. Now, check that you indeed have RM1 running in Hyperchem: draw the molecule of hydrogen fluoride, HF; choose AM1 in the dropdown menu Setup/Semiempirical; and optimize its geometry. If the optimized HF bond length is 0.917 angstroms, then RM1 has been correctly installed.

That is it! From now on, whenever you select AM1 in the HyperChem dropdown menu Setup/Semiempiricalyour calculations will actually be RM1 calculations. And that will be so, even though the log file will still show AM1 written in the output results, as if it was the chosen model. This happens because we only changed the values of the parameters - and nothing further.

Warning: if you are using RM1 in HyperChem, please make sure that your molecular system contains only atoms of H, C, N, O, P, S, F, CL, Br and I. These are the only ones which have, so far, parameters in RM1. However, these are enough for modeling most molecular systems of importance to organic chemistry, biochemistry and pharmaceutical research.

If you want to undo these changes and have AM1 back running in HyperChem, simply do the following:

  1. Rename Am1_1.abp to Am1_1.abp_rm1; Am1_2.abp to Am1_2.abp_rm1; and Am1_3.abp to Am1_3.abp_rm1;
  2. Rename Am1_1.abp_am1 to Am1_1.abp; Am1_2.abp_am1 to Am1_2.abp; and Am1_3.abp_am1 to Am1_3.abp.
  3. Now, check that you indeed have AM1 back running in HyperChem: draw the molecule of hydrogen fluoride, HF; choose AM1 in the dropdown menu Setup/Semiempirical; and optimize its geometry. If the optimized HF bond length is 0.826 angstroms, then AM1 has been correctly brought back.

If you run into any kind of trouble; or if you lose the original am1_*.abp files, please uninstall HyperChem, and then reinstall it again.

Although we will try to solve users difficulties to our best, we cannot guarantee that we will be able to do that. Indeed, we do not have the means to fully support RM1 on a worldwide basis. Please, be patient if we do not reply to your e-mails in a timely fashion.
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