[molpro-user] To understand the reason for difference betweeen two outputs for the same situation developed by MOLPRO

Sham K shaawm at gmail.com
Thu Nov 16 09:05:06 CET 2017

Hello Users,

One simple possibility is to check nuclear repulsion energy to satisfy if
two geometries are the same.

There is another nice way to check if two structures (with same atoms and
the order in which they are listed is same) with different xyz data are
same. This comes from an elegant algorithm known as Kabsch algorithm - for
details of how it works see - https://en.wikipedia.org/wiki/Kabsch_algorithm

It calculates an RMSD between two structures. For the case here, using the
calculate_rmsd program from github, download it from

sham at shree:~/junk$ ./calculate_rmsd.py a.xyz b.xyz
Normal RMSD: 0.305543115084
Kabsch RMSD: 7.14474667163e-06
Quater RMSD: 7.14474667163e-06

Showing that two structures are indeed the same.

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