Domingos,

The basis sets listed in NWChem come from the bse.pnl.gov Basis Set Exchange, and are based on what is published in the papers associated with it. I would recommend you find the paper of the basis set you are using. There you will most likely find a description as to what are the occupied contracted functions and which are the polarization type functions.

Generally, you want to remove a column and the column with the largest contraction coefficients (for example this would be the right most column in the example you listed) are the more diffuse and lowest NO contractions.

Bert

[QUOTE=Ddcr Jun 21st 6:36 pm]Dear all,

I'm planning to use the relativistic ANO-RCC basis set (relativistic contracted

atomic natural orbitals) for some alkaline clusters. Since it is a very expensive

basis I intend to use a reduced version of it (a subset) by throwing away some general

contractions (one or two contractions per angular momentum).

From the literature I gathered recently I can do this straight eliminatiom without

recontraction, since the contraction coefficients for the contracted ANO basis set

are the expansion coefficients in terms of the uncontracted set of natural orbitals

(i.e. eigenfunctions of the one-electron density matrix D). The only criteria is

to eliminate coefficients associated to very small eigenvalues called "natural

occupation numbers" (NOs).

Does anybody out there knows if the contraction coefficients listed in the NWCHEM

format are ordered by decreasing NO, something like the following example:

decreasing NO

---------------------------------------------------------->

| Li S

| 9497.9344000000 0.00009669 -0.00001245 ... -0.00030282

| 1416.8112000000 0.00060871 -0.00007839 ... -0.00010821

| 321.4599400000 0.00310152 -0.00040071 ... -0.01796344

| 91.1241630000 0.01266905 -0.00164525 ... -0.03355851

| 29.9998910000 0.04248013 -0.00563460 ... -1.31291580

| 11.0176310000 0.11501833 -0.01590781 ... 1.79208540

| 4.3728010000 0.23986501 -0.03612582 ... 0.46208290

| 1.8312560000 0.35843001 -0.06459928 ... -4.24788632

| 0.8022610000 0.30485278 -0.10083218 ... 6.59391203

| 0.3626480000 0.08824262 -0.09757614 ... -4.97139570

| 0.1139950000 -0.00084459 0.23012159 ... 1.99865736

| 0.0512370000 -0.00794396 0.61023898 ... 0.09345883

| 0.0224680000 -0.00376442 0.28494061 ... -1.21940644

| 0.0078600000 -0.00008869 0.00402690 ... 0.71451366

v

decreasing

exponents

I apologize if this is a very specialized topic for this forum, but I would

really appreciate if someone could help me somewhow, at least redirecting me to

the right path. I seemed to have reached a dead end here.

Best regards,

Domingos