Efficient optimization of the basis set is key to achieving a very high accuracy in variational calculations of molecular systems employing basis functions that are explicitly dependent on the interelectron distances. In this work we present a method for a systematic enlargement of basis sets of explicitly correlated functions based on the iterative-complement-interaction approach developed by Nakatsuji [Phys. Rev. Lett.93, 030403 (2004)]. We illustrate the performance of the method in the variational calculations of H3 where we use explicitly correlated Gaussian functions with shifted centers. The total variational energy (−1.674 547 421 Hartree) and the binding energy (15.74cm1) obtained in the calculation with 1000 Gaussians are the most accurate results to date.

1.
D. B.
Kinghorn
and
R. D.
Poshusta
,
Int. J. Quantum Chem.
62
,
223
(
1997
).
2.
S.
Bubin
,
M.
Cafiero
, and
L.
Adamowicz
,
Adv. Chem. Phys.
131
,
377
(
2005
).
3.
K.
Pachucki
and
J.
Komasa
,
Phys. Rev. Lett.
92
,
213001
(
2004
).
4.
M.
Stanke
,
D.
Kedziera
,
M.
Molski
,
S.
Bubin
,
M.
Barysz
, and
L.
Adamowicz
,
Phys. Rev. Lett.
96
,
233002
(
2006
).
5.
W.
Cencek
,
J.
Komasa
,
K.
Pachucki
, and
K.
Szalewicz
,
Phys. Rev. Lett.
95
,
233004
(
2005
).
6.
M.
Cafiero
and
L.
Adamowicz
,
Chem. Phys. Lett.
387
,
136
(
2004
).
7.
M.
Cafiero
and
L.
Adamowicz
,
Chem. Phys. Lett.
335
,
404
(
2001
).
8.
M.
Pavanello
and
L.
Adamowicz
,
J. Chem. Phys.
130
,
034104
(
2009
).
9.
M.
Pavanello
,
W.
Tung
,
F.
Leonarski
, and
L.
Adamowicz
,
J. Chem. Phys.
130
,
074105
(
2009
).
10.
R.
Pauncz
,
Spin Eigenfunctions
(
Plenum
,
New York
,
1979
).
11.
T.
Kato
,
Commun. Pure Appl. Math.
10
,
151
(
1957
).
12.
K.
Patkowski
,
W.
Cencek
,
P.
Jankowski
,
K.
Szalewicz
,
J. B.
Mehl
,
G.
Garberoglio
, and
A. H.
Harvey
,
J. Chem. Phys.
129
,
094304
(
2008
).
13.
R.
Krishnan
,
J. S.
Binkley
,
R.
Seeger
, and
J. A.
Pople
,
J. Chem. Phys.
72
,
650
(
1980
).
14.
H.
Nakatsuji
,
Phys. Rev. Lett.
93
,
030403
(
2004
).
15.
S. G.
Nash
,
SIAM (Soc. Ind. Appl. Math.) J. Numer. Anal.
21
,
770
(
1984
).
16.
B.
Liu
,
J. Chem. Phys.
58
,
1925
(
1973
).
17.
D. G.
Truhlar
and
C. J.
Horowitz
,
J. Chem. Phys.
68
,
2466
(
1978
).
18.
Y. S. M.
Wu
,
A.
Kupperman
, and
J. B.
Anderson
,
Phys. Chem. Chem. Phys.
6
,
929
(
1999
).
19.
K. T.
Tang
and
J. P.
Toennies
,
Chem. Phys. Lett.
151
,
301
(
1988
).
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