CCL: Static polarizability of Atoms with Gaussian or Gamess

 Sent to CCL by: Susi Lehtola [susi.lehtola^^^helsinki.fi]
 Dear Krishna,
 your basis set is simply too small: 6-311+G(2d,p) is a double-zeta basis
 set, which does not even include diffuse functions on hydrogen. You
 need to go to bigger basis sets. Repeating your calculation I get
 Basis			Polarizability (bohr^3)
 6-311+G(2d,p)		0.59
 cc-pVDZ			0.63
 cc-pVTZ			1.88
 cc-pVQZ			2.74
 cc-pV5Z			3.22
 cc-pV6Z			3.57
 You see that the convergence is very slow in terms of the basis set
 size. This is often an indicator of important functions missing from
 the basis set. Indeed, electrical properties like the dipole moment or
 polarizability are well-known to be sensitive to diffuse functions.
 Even augmented Pople sets, however, yield very poor results:
 6-31++G**		0.25
 6-311++G**		0.59
 Repeating the calculations in the augmented Dunning series gives much
 better convergence
 aug-cc-pVDZ		4.29
 aug-cc-pVTZ		4.48
 aug-cc-pVQZ		4.50
 aug-cc-pV5Z		4.49
 aug-cc-pV6Z		4.49
 The result is essentially converged already with the triple-zeta basis,
 and it is in excellent agreement with the experimental value of 4.50.
 --
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 Mr. Susi Lehtola, PhD             Adjunct Professor
 susi.lehtola]![helsinki.fi          University of Helsinki
 http://susilehtola.github.io/     Finland
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 Susi Lehtola, FT                  dosentti
 susi.lehtola]![helsinki.fi          Helsingin yliopisto
 http://susilehtola.github.io/
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