National Institute of Standards and Technology

Computational Chemistry Comparison and Benchmark DataBase
Release 22	May 2022
NIST Standard Reference Database 101

I	Introduction
II	Experimental data
III	Calculated data
IV	Data comparisons
V	Cost comparisons
VI	Input and output files
VII	Tutorials and Units
VIII	Links to other sites
IX	Feedback
X	Older CCCBDB versions
XII	Geometries
XIII	Vibrations
XIV	Reaction data
XV	Entropy data
XVI	Bibliographic data
XVII	Ion data
XVIII	Bad calculations
XIX	Index of properties
XX	H-bond dimers
XXI	Oddities

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The National Institute of Standards and Technology (NIST) is an agency of the U.S. Department of Commerce.

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III.G.10.a.

Energy differences between frozen core and full core for MP2/3-21G

For ()

	Energy (hartrees)
frozen core	-92.0585885
correlated core	-92.0609293
difference	-0.0023408

	Energy (hartrees)
frozen core	-92.0627653
correlated core	-92.0609293
difference	0.0018360

	Energy (hartrees)
frozen core	-92.0585885
correlated core	-92.0659809
difference	-0.0073924

	Energy (hartrees)
frozen core	-92.0627653
correlated core	-92.0659809
difference	-0.0032156