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IV.D.1. (XII.C.1.)

Geometry Comparison

As4 (Arsenic tetramer)


distance is atom 1 (As) to atom 2 (As)

Experimental bond length is 2.435  Å

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Calculated bond length in Å
Methods with predefined basis sets
semi-empirical PM3 2.392
PM6 2.512
composite G2 2.399
G3 2.422
G3B3 2.463
CBS-Q 2.401

Calculated bond length in Å
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) TZVP cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ
hartree fock HF 2.363 2.584 2.410 2.541 2.400 2.400 2.404 2.424 2.424 2.361 2.422 2.424 2.418 2.416 2.428 2.418 2.416
density functional LSDA 2.363 2.406 2.406 2.530 2.404 2.404 2.409 2.425 2.425 2.358 2.424 2.431 2.417   2.431 2.417  
SVWN   2.559     2.404 2.404 2.409 2.425 2.425 2.358   2.431 2.417   2.431 2.417  
BLYP 2.403 2.620 2.468 2.598 2.472 2.472 2.477 2.498 2.498 2.415 2.497 2.502 2.490        
B1B95 2.370 2.407 2.407 2.533 2.398 2.398 2.402 2.423 2.423 2.356 2.423 2.424 2.417   2.426 2.418  
B3LYP 2.390 2.597 2.440 2.569 2.439 2.439 2.444 2.463 2.463 2.389 2.462 2.467 2.455 2.454 2.468 2.456 2.453
B3LYPultrafine         2.439             2.467 2.455   2.468 2.456  
B3PW91 2.382 2.585 2.425 2.551 2.418 2.418 2.422 2.441 2.441 2.372 2.441 2.444 2.434        
mPW1PW91 2.378 2.580 2.419 2.544 2.411 2.411 2.415 2.434 2.434 2.367 2.434 2.437 2.428   2.439 2.428  
M06-2X 2.365 2.587 2.425 2.540 2.402 2.402 2.406 2.429 2.429 2.365 2.435 2.428 2.429   2.432 2.429  
PBEPBE 2.387 2.602 2.443 2.572 2.438 2.438 2.443 2.464 2.464 2.388 2.464 2.466 2.457   2.468 2.457  
PBEPBEultrafine         2.438             2.466 2.457   2.468 2.457  
PBE1PBE 2.376 2.418 2.418 2.545 2.409 2.409 2.413 2.433 2.433 2.366 2.432 2.435 2.426   2.437 2.427  
HSEh1PBE 2.376 2.582 2.420 2.549 2.413 2.413 2.417 2.437 2.437 2.368 2.436 2.439 2.430   2.441 2.431  
TPSSh         2.415   2.419           2.432        
Moller Plesset perturbation MP2 2.424 2.665 2.441 2.629 2.447 2.447 2.452 2.472 2.472 2.387 2.449 2.458 2.431 2.412 2.472 2.431 2.408
MP2=FULL 2.424 2.665 2.438 2.629 2.433 2.433 2.438 2.460 2.460 2.360 2.448 2.454 2.417 2.408 2.469 2.407 2.399
MP3         2.447   2.446                    
MP3=FULL         2.435   2.440                    
MP4   2.662     2.458       2.484   2.466 2.473 2.443        
MP4=FULL   2.662     2.444       2.474     2.469 2.429        
Configuration interaction CID   2.622 2.421 2.583 2.422     2.443                  
CISD   2.623 2.422 2.584 2.423     2.444                  
Quadratic configuration interaction QCISD   2.656 2.442 2.618 2.445 2.445 2.450 2.469 2.469 2.384 2.452 2.460 2.429   2.468 2.428  
QCISD(T)         2.458           2.466 2.473 2.442   2.482 2.442  
Coupled Cluster CCD   2.652 2.440 2.614 2.443 2.443 2.447 2.465 2.465 2.381 2.448 2.457 2.426   2.465 2.425  
CCSD         2.445           2.451 2.459 2.429   2.467 2.428  
CCSD=FULL         2.433           2.450 2.456 2.417        
CCSD(T)         2.457           2.465 2.472 2.442   2.482 2.441  
CCSD(T)=FULL         2.444           2.464 2.469 2.429   2.480    

Calculated bond length in Å
Methods with effective core potentials (select basis sets)
CEP-31G CEP-31G* CEP-121G CEP-121G* LANL2DZ SDD
hartree fock HF 2.514   2.514   2.579 2.518
density functional B3LYP 2.565   2.565   2.623 2.562
Moller Plesset perturbation MP2 2.625   2.625   2.684 2.620
Values that are outliers may reflect incorrect atom numbering for different levels of theory.
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