Pseudo

Description

This keyword requests that a model potential be substituted for the core electrons. The pseudopotential must be used with a compatible basis set. Gaussian supports a new effective core potential (ECP) input format (similar to that used by ExtraBasis) which is described in the Format tab.

Without any options, this keyword defaults to Pseudo=Read. However, the Cards option is by far its most-used mode. When reading-in pseudopotentials, do not give them the same names as any internally-stored pseudopotentials: CEP, CHF, LANL1, LANL2, LP-31, SDD, and SHC.

If used with ONIOM, the Pseudo and keyword applies to all layer of the ONIOM. If you want to read in ECPs only for one ONIOM layer, then use the GenECP keyword instead.

Options

Read

Read pseudopotential data from the input stream. Input is described in the next subsection below. Cards is a synonym for Read.

SOScal

When reading pseudopotentials from input using Pseudo=Read, scale the spin-orbit coefficients (if present) by 2/L as appropriate for published CRENBL potentials. The default is not to scale, which is appropriate for Dolg (Stuttgart) potentials.

CHF

Requests the Coreless Hartree-Fock potentials. This option is normally used with the LP-31G basis sets.

SHC

Requests the SHC potentials.

LANL1

Requests the LANL1 potentials.

LANL2

Requests the LANL2 potentials.

Old

Read pseudopotential data using the old format (used by Gaussian 92 and earlier versions).

Format

Full ECP Input Format

Effective Core Potential operators are sums of products of polynomial radial functions, Gaussian radial functions and angular momentum projection operators. ECP input therefore specifies which potential to use on each atomic center, and then includes a collection of triplets of:

(coefficient, power of R, exponent)

for each potential for each term in each angular momentum of the ECP. Since only the first few angular momentum components have different terms, the potential is expressed as (1) terms for the general case, typically d or f and higher projection, and (2) the extra terms for each special angular momentum. Thus for an LP-31G potential, which includes special s and p projected terms, the input includes the general (d and higher) term, the s-d term (i.e., what to add to the general term to make the s component) and the p-d term.

All ECP input is free-format. Each block is introduced by a line containing the center numbers (from the molecule specification) and/or atomic symbols, specifying the atoms and/or atoms types to which it applies (just as for general basis set input-see the discussion of the Gen keyword). The list ends with a value of 0.

The pseudopotential for those centers/atoms follows:

Name,Max,ICore

Name of the potential, maximum angular momentum of the potential (i.e., 2 if there are special s and p projections, 3 if there are s, p, and d projections), and number of core electrons replaced by the potential. If Name matches the name of a previous potential, that potential is reused and no further input other than the terminator line is required.

For each component (I=1 to Max) of the current potential, a group of terms is read, containing the following information:

Title

A description of the block, not otherwise used.

NTerm

Number of terms in the block.

NPower,Expon,Coeff[,SO]

Power of R, exponent, and coefficient for each of the NTerm terms. NPower includes the R² Jacobian factor. The optional SO coefficient is for use with ECP basis sets which include this term.

Simplified ECP Input Format

Gaussian adds flexibility to ECP input by allowing it to include pre-defined basis sets names. An ECP definition may be replaced by a line containing the standard keyword for a pre-defined basis set. In this case, the ECPs within the specified basis set corresponding to the specified atom type(s) will be used for that atom (see the examples).

Keywords

In Pseudo input, keywords for these ECPs are of the form XYn where n is the number of core electrons which are replaced by the pseudopotential and X denotes the reference system used for generating the pseudopotential (S for a single-valence-electron ion or M for a neutral atom).

Y specifies the theoretical level of the reference data: HF for Hartree-Fock, WB for Wood-Boring quasi-relativistic and DF for Dirac-Fock relativistic. For one- or two-valence electron atoms SDF is a good choice; otherwise MWB or MDF is recommended (although for small atoms or for the consideration of relativistic effects, the corresponding SHF and MHF pseudopotentials may be useful).

SD ECP Availability

The Stuttgart/Dresden ECPs are not uniformly available across the periodic table. The following table shows the availability of the various XY combinations, along with valid values for n. The Defaults columns list the equivalencies for the SDD keyword (which selects an all electron basis set through Cl and ECPs thereafter) and when IOp(3/6) is set to 6 (which selects ECPs for all elements).

Note: These ECPs are not available for elements 87 (Fr), 88 (Ra), and 105 and higher.

				Valid values of n for given values of X and Y
Z	Atom	IOp(3/6=6) Default	SDD keyword Default	MWB	SDF	SHF	MDF	MHF
1	H	D95	D95
2	He	D95	D95
3	Li	SDF2	D95
4	Be	SDF2	D95		2
5	B	MWB2	D95	2	2
6	C	MWB2	D95	2	2
7	N	MWB2	D95	2	2
8	O	MWB2	D95	2	2
9	F	MWB2	D95	2	2
10	Ne	MWB2	D95	2				2
11	Na	SDF10	6-31G		10
12	Mg	SDF10	6-31G		10
13	Al	MWB10	D95	10	10
14	Si	MWB10	D95	10	10
15	P	MWB10	D95	10	10
16	S	MWB10	D95	10	10
17	Cl	MWB10	D95	10	10
18	Ar	MWB10	6-31G	10				10
19	K	MWB10	MWB10	10	18	18
20	Ca	MWB10	MWB10	10	18	18
21	Sc	MDF10	MDF10				10	10
22	Ti	MDF10	MDF10				10	10
23	V	MDF10	MDF10				10	10
24	Cr	MDF10	MDF10				10	10
25	Mn	MDF10	MDF10				10	10
26	Fe	MDF10	MDF10				10	10
27	Co	MDF10	MDF10				10	10
28	Ni	MDF10	MDF10				10	10
29	Cu	MDF10	MDF10			28	10	10
30	Zn	MDF10	MDF10	28	28		10	10
31	Ga	MWB28	MWB28	28	28
32	Ge	MWB28	MWB28	28	28	28
33	As	MWB28	MWB28	28	28
34	Se	MWB28	MWB28	28	28
35	Br	MWB28	MWB28	28	28
36	Kr	MWB28	MWB28	28				28
37	Rb	MWB28	MWB28	28	36	36
38	Sr	MWB28	MWB28	28	36	36
39	Y	MWB28	MWB28	28				28
40	Zr	MWB28	MWB28	28				28
41	Nb	MWB28	MWB28	28				28
42	Mo	MWB28	MWB28	28				28
43	Tc	MWB28	MWB28	28				28
44	Ru	MWB28	MWB28	28				28
45	Rh	MWB28	MWB28	28				28
46	Pd	MWB28	MWB28	28				28
47	Ag	MWB28	MWB28	28		46		28
48	Cd	MWB28	MWB28	28				28
49	In	MWB46	MWB46	46	46
50	Sn	MWB46	MWB46	46	46
51	Sb	MWB46	MWB46	46	46
52	Te	MWB46	MWB46	46	46
53	I	MWB46	MWB46	46	46		46
54	Xe	MWB46	MWB46	46				46
55	Cs	MWB46	MWB46	46	54	54
56	Ba	MWB46	MWB46	46	54
57	La	MWB28	MWB28	28, 46, 47				46, 47
58	Ce	MWB28	MWB28	28, 47, 48				47, 48
59	Pr	MWB28	MWB28	28, 48, 49				48, 49
60	Nd	MWB28	MWB28	28, 49, 50				49, 50
61	Pm	MWB28	MWB28	28, 50, 51				50, 51
62	Sm	MWB28	MWB28	28, 51, 52				51, 52
63	Eu	MWB28	MWB28	28, 52, 53				52, 53
64	Gd	MWB28	MWB28	28, 53, 54				53, 54
65	Tb	MWB28	MWB28	28, 54, 55				54, 55
66	Dy	MWB28	MWB28	28, 55, 56				55, 56
67	Ho	MWB28	MWB28	28, 56, 57				56, 57
68	Er	MWB28	MWB28	28, 57, 58				57, 58
69	Tm	MWB28	MWB28	28, 58, 59				58, 59
70	Yb	MWB28	MWB28	28, 59				59
71	Lu	MWB60	MWB60	28, 60				60
72	Hf	MWB60	MWB60	60				60
73	Ta	MWB60	MWB60	60				60
74	W	MWB60	MWB60	60				60
75	Re	MWB60	MWB60	60				60
76	Os	MWB60	MWB60	60				60
77	Ir	MWB60	MWB60	60				60
78	Pt	MWB60	MWB60	60				60
79	Au	MWB60	MWB60	60		78	60	60
80	Hg	MWB60	MWB60	60, 78			60	60, 78
81	Tl	MWB78	MWB78	78				78
82	Pb	MWB78	MWB78	78				78
83	Bi	MWB78	MWB78	78				78
84	Po	MWB78	MWB78	78				78
85	At	MWB78	MWB78	78				78
86	Rn	MWB78	MWB78	78				78
89	Ac	MWB60	MWB60	60				60
90	Th	MWB60	MWB60	60				60
91	Pa	MWB60	MWB60	60				60
92	U	MWB60	MWB60	60				60
93	Np	MWB60	MWB60	60				60
94	Pu	MWB60	MWB60	60				60
95	Am	MWB60	MWB60	60				60
96	Cm	MWB60	MWB60	60				60
97	Bk	MWB60	MWB60	60				60
98	Cf	MWB60	MWB60	60				60
99	Es	MWB60	MWB60	60				60
100	Em	MWB60	MWB60	60				60
101	Md	MWB60	MWB60	60				60
102	No	MWB60	MWB60	60				60
103	Lr	MWB60	MWB60	60				60
104	Rf						92

Related Keywords

ChkBasis, ExtraBasis, Gen, GenECP

Examples

Specifying an ECP. This input file runs an RHF/LP-31G calculation on hydrogen peroxide, with the basis set and ECP data read from the input file:

# HF/Gen Pseudo=Read Test

Hydrogen peroxide

0,1
O
H,1,R2
O,1,R3,2,A3
H,3,R2,1,A3,2,180.,0

R2=0.96
R3=1.48
A3=109.47

General basis set input
****

O 0	ECPs for the oxygen atoms.
OLP 2 2	ECP name=OLP, applies to d & higher, replaces 2 electrons.
D component	Description for the general terms.
3	Number of terms to follow.
1 80.0000000 -1.60000000
1 30.0000000 -0.40000000
2 1.0953760 -0.06623814
S-D projection	Corrections for projected terms (lowest angular momentum).
3
0 0.9212952 0.39552179
0 28.6481971 2.51654843
2 9.3033500 17.04478500



P-D	Corrections for projected terms (highest angular momentum).
2
2 52.3427019 27.97790770
2 30.7220233 -16.49630500
	Blank line indicates end of the ECP block.

The basis set data follows the molecule specification section. The first line of the ECP data requests that a potential be read in (type 7) for atoms number 1 and 3 (the oxygen atoms). No potential is to be used for atoms 2 and 4 (the hydrogen atoms).

The second line of ECP data begins the input for the centers requiring a read-in potential: in this case, oxygen atoms. The potential on these centers is named OLP, it is a general term and applies to angular momentum 2 (d) and higher, and the potential replaces two electrons. Next comes a title for the general term (D component), and the number of components of that term (3); the individual components follow on the next 3 lines. Next come the corrections for the projected terms in two sections, lowest angular momentum first. Each section again consists of a title line, the number of terms to follow, and then the terms themselves.

Using Standard Basis Set Keywords to Specify ECPs. The following input file illustrates the use of the simplified ECP input format:

# Becke3LYP/Gen Pseudo=Read Opt Test

HF/6-31G(d) Opt of Cr(CO)6

0 1
Cr 0.0 0.0 0.0
molecule specification continues …

C O 0
6-31G(d)
****
Cr 0
LANL2DZ
****

Cr 0	ECP for chromium atom.
LANL2DZ	Use the ECP in this basis set.

Last updated on: 16 December 2020. [G16 Rev. C.01]


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