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IV.A.4. (XIV.F.)

Relative enthalpies of isomers - Comparison of 0K enthalpies (kJ mol-1)

Isomers of C2H2

index Species CAS number Name Relative experimental enthalpy (kJ mol-1) sketch
a C2H2 74862 Acetylene 0.0 sketch of Acetylene
b CCH2 2143693 vinylidene   sketch of vinylidene
The calculated enthalpies include the calculated and scaled vibrational zero-point energy.
Methods with predefined basis sets
composite G1 0.0 a
170.2 b
G2MP2 0.0 a
170.3 b
G2 0.0 a
170.5 b
G3 0.0 a
172.5 b
G3MP2 0.0 a
171.6 b
CBS-Q 0.0 a
174.8 b
Methods with standard basis sets
STO-3G 3-21G 3-21G* 6-31G 6-31G* 6-31G** 6-31+G** 6-311G* 6-311G** 6-31G(2df,p) 6-311+G(3df,2p) TZVP cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ cc-pV(T+d)Z cc-pCVDZ cc-pCVTZ
hartree fock HF 0.0 a
167.6 b 		0.0 a
151.7 b 		0.0 a
151.7 b 		0.0 a
141.9 b 		0.0 a
134.2 b 		0.0 a
134.1 b 		  0.0 a
134.6 b 		0.0 a
138.4 b 		0.0 a
138.1 b 		0.0 a
139.0 b 		  0.0 a
129.0 b 		0.0 a
139.0 b 		0.0 a
140.2 b 		0.0 a
126.5 b 		0.0 a
138.3 b 		0.0 a
139.8 b 		0.0 a
139.0 b 		   
density functional LSDA 0.0 a
236.0 b 		0.0 a
209.8 b 		0.0 a
209.8 b 		0.0 a
204.9 b 		0.0 a
190.0 b 		0.0 a
189.8 b 		0.0 a
184.1 b 		0.0 a
193.0 b 		        0.0 a
172.4 b 		    0.0 a
170.9 b 		         
BLYP 0.0 a
195.2 b 		0.0 a
184.0 b 		0.0 a
184.0 b 		0.0 a
179.9 b 		0.0 a
167.5 b 		0.0 a
167.9 b 		0.0 a
163.1 b 		0.0 a
171.8 b 		0.0 a
175.1 b 		0.0 a
173.3 b 		    0.0 a
165.3 b 		0.0 a
175.0 b 		        0.0 a
175.0 b 		   
B1B95 0.0 a
207.2 b 		0.0 a
189.0 b 		0.0 a
189.0 b 		0.0 a
185.2 b 		0.0 a
168.7 b 		0.0 a
172.3 b 		0.0 a
168.0 b 		0.0 a
173.3 b 		0.0 a
176.4 b 		      0.0 a
168.5 b 		0.0 a
173.2 b 		        0.0 a
173.2 b 		   
B3LYP 0.0 a
196.0 b 		0.0 a
183.2 b 		0.0 a
183.2 b 		0.0 a
178.0 b 		0.0 a
165.6 b 		0.0 a
166.0 b 		0.0 a
162.0 b 		0.0 a
169.6 b 		0.0 a
173.1 b 		0.0 a
171.6 b 		  0.0 a
173.4 b 		0.0 a
163.2 b 		0.0 a
173.1 b 		0.0 a
173.7 b 		0.0 a
160.3 b 		0.0 a
172.1 b 		0.0 a
172.9 b 		0.0 a
173.1 b 		   
B3LYPultrafine         0.0 a
165.6 b 		                               
B3PW91 0.0 a
203.1 b 		0.0 a
186.3 b 		0.0 a
186.3 b 		0.0 a
181.9 b 		0.0 a
169.7 b 		0.0 a
170.1 b 		0.0 a
166.3 b 		0.0 a
172.6 b 		0.0 a
175.9 b 		0.0 a
175.4 b 		    0.0 a
167.2 b 		0.0 a
176.2 b 		        0.0 a
176.2 b 		   
mPW1PW91 0.0 a
202.8 b 		0.0 a
183.5 b 		0.0 a
186.1 b 		0.0 a
181.6 b 		0.0 a
167.1 b 		0.0 a
167.5 b 		0.0 a
163.7 b 		0.0 a
169.6 b 		0.0 a
175.0 b 		0.0 a
174.8 b 		    0.0 a
164.4 b 		0.0 a
173.4 b 		        0.0 a
173.4 b 		   
PBEPBE 0.0 a
209.2 b 		0.0 a
190.6 b 		0.0 a
190.6 b 		0.0 a
187.6 b 		0.0 a
175.0 b 		0.0 a
175.4 b 		0.0 a
170.4 b 		0.0 a
177.4 b 		0.0 a
180.5 b 		0.0 a
179.8 b 		    0.0 a
172.4 b 		0.0 a
180.6 b 		    0.0 a
179.3 b 		  0.0 a
180.6 b 		   
Moller Plesset perturbation MP2FC 0.0 a
278.8 b 		0.0 a
233.4 b 		0.0 a
233.4 b 		0.0 a
227.0 b 		0.0 a
209.1 b 		0.0 a
206.3 b 		0.0 a
199.6 b 		0.0 a
207.8 b 		0.0 a
208.4 b 		0.0 a
215.5 b 		  0.0 a
210.5 b 		0.0 a
199.7 b 		0.0 a
209.9 b 		  0.0 a
196.3 b 		0.0 a
208.7 b 		  0.0 a
209.9 b 		0.0 a
199.8 b 		0.0 a
209.9 b
MP2FU   0.0 a
233.5 b 		    0.0 a
210.4 b 		0.0 a
207.7 b 		0.0 a
201.0 b 		0.0 a
208.7 b 		0.0 a
209.6 b 		      0.0 a
200.6 b 		0.0 a
215.4 b 		  0.0 a
197.3 b 		0.0 a
212.3 b 		  0.0 a
215.4 b 		0.0 a
200.3 b 		0.0 a
211.1 b
MP4         0.0 a
185.0 b 		                               
Configuration interaction CID         0.0 a
167.7 b 		    0.0 a
165.9 b 		                         
CISD         0.0 a
167.8 b 		                               
Quadratic configuration interaction QCISD   0.0 a
205.2 b 		    0.0 a
172.2 b 		0.0 a
170.6 b 		0.0 a
164.3 b 		0.0 a
169.1 b 		0.0 a
171.2 b 		      0.0 a
161.2 b 		0.0 a
171.9 b 		        0.0 a
171.9 b 		   
QCISD(T)         0.0 a
177.9 b 		                               
Coupled Cluster CCD         0.0 a
172.3 b 		  0.0 a
164.0 b 		0.0 a
169.6 b 		        0.0 a
161.3 b 		0.0 a
172.4 b 		             
CCSD         0.0 a
171.7 b 		                               
CCSD(T)         0.0 a
177.9 b 		  0.0 a
210.3 b 		  0.0 a
176.8 b 		      0.0 a
166.4 b 		0.0 a
177.9 b 		  0.0 a
161.5 b 		0.0 a
176.5 b 		  0.0 a
177.9 b 		0.0 a
166.6 b 		0.0 a
178.1 b
CCSD(T)=FULL         0.0 a
179.4 b 		              0.0 a
167.5 b 		0.0 a
184.6 b 		  0.0 a
162.8 b 		    0.0 a
184.6 b 		0.0 a
167.5 b 		0.0 a
180.1 b
Methods with effective core potentials (select basis sets)
CEP-31G CEP-31G* CEP-121G CEP-121G* LANL2DZ SDD
hartree fock HF 0.0 a
108.9 b 		0.0 a
100.5 b 		0.0 a
133.6 b 		0.0 a
129.1 b 		0.0 a
142.0 b 		0.0 a
142.5 b
density functional B1B95 0.0 a
163.7 b 		0.0 a
149.1 b 		       
B3LYP 0.0 a
138.8 b 		0.0 a
126.5 b 		0.0 a
155.2 b 		0.0 a
147.5 b 		0.0 a
175.6 b 		0.0 a
175.3 b
Moller Plesset perturbation MP2FC 0.0 a
190.6 b 		0.0 a
174.9 b 		0.0 a
210.5 b 		0.0 a
196.1 b 		0.0 a
225.2 b 		0.0 a
225.1 b
Single point energy calculations (select basis sets)
cc-pVTZ cc-pV(T+d)Z
Moller Plesset perturbation MP2FC// B3LYP/6-31G* 0.0 a
211.1 b 		 
Coupled Cluster CCSD(T)// B3LYP/6-31G* 0.0 a
178.2 b 		 
CCSD(T)//B3LYP/6-31G(2df,p) 0.0 a
176.4 b 		0.0 a
176.4 b
NC = not calculated
For descriptions of the methods (AM1, HF, MP2, ...) and basis sets (3-21G, 3-21G*, 6-31G, ...) see the glossary in section I.C. Predefined means the basis set used is determined by the method.
gaw refers to the group additivity method implemeted in the NIST Chemistry Webbook.

See section III.C.1 List or set vibrational scaling factors to change the scale factors used here.
See section III.C.2 Calculate a vibrational scaling factor for a given set of molecules to determine the least squares best scaling factor.