Available PAW potentials: Difference between revisions

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For some elements several PAW versions exist. The standard version has no extension. The extension _h implies that the potential is harder than the standard potential and hence requires a greater energy cutoff. The extension _s means that the potential is softer than the standard version. The extensions _pv and _sv imply that the <math>p</math> and <math>s</math> semi-core states are treated as valence states (i.e. for V_pv the <math>3p</math> states are treated as valence states, and for V_sv the <math>3s</math> and <math>3p</math> states are treated as valence states). PAW files with an extension _d, treat the <math>d</math> semi core states as valence states (for Ga_d the <math>3d</math> states are treated as valence states).  
For some elements several PAW versions exist. The standard version has no extension. The extension _h implies that the potential is harder than the standard potential and hence requires a greater energy cutoff. The extension _s means that the potential is softer than the standard version. The extensions _pv and _sv imply that the <math>p</math> and <math>s</math> semi-core states are treated as valence states (i.e. for V_pv the <math>3p</math> states are treated as valence states, and for V_sv the <math>3s</math> and <math>3p</math> states are treated as valence states). PAW files with an extension _d, treat the <math>d</math> semi core states as valence states (for Ga_d the <math>3d</math> states are treated as valence states).  


The valence configuration underlying each PAW potential can be inferred from the {{TAG|ZVAL}} and the table below <code>Atomic configuration</code> in the [[POTCAR]] file. The table lists first the core states and then the valence states. Hence, the final rows those occupancies add up to {{TAG|ZVAL}} comprise the valence configuration. Note that this can differ from the ground-state configuration in vacuum and that the rows are not ordered by energy. For instance, for Gd_3 strongly localized, semi-core f electrons are treated as core states despite being high in energy compared to other valence states.   
The valence configuration underlying each PAW potential can be inferred from the {{TAG|ZVAL}} tag and the table written below <code>Atomic configuration</code> in the [[POTCAR]] file. The table lists first the core states and then the valence states. Hence, the final rows those occupancies add up to {{TAG|ZVAL}} comprise the valence configuration. Note that this can differ from the ground-state configuration in vacuum and that the rows are not ordered by energy. For instance, for Gd_3 strongly localized, semi-core <math>f</math> electrons are treated as core states despite being higher in energy than other valence states.   


In the following, we will present the available PAW potentials. All distributed potentials have been tested using standard DFT-"benchmark" runs; see the ''data_base'' file in the released tar files. We strongly recommend using the [[POTCAR]]-files version 5.4 that is available as a download on the VASP Portal. The currently distributed [[POTCAR]] files of version 5.4 possess a unique SHA hash. The [[POTCAR]]-files version 5.2 is also quite popular and has been used in the [https://wiki.materialsproject.org/Pseudopotentials_Choice Materials Project]. Differences between version 5.4 and 5.2 are usually small and limited to few elements/POTCAR files. Each [[POTCAR]] file of version 5.2 that is presently available on the VASP Portal also possesses a unique SHA hash, and they have been slightly edited in the text part of the headers, which is irrelevant to VASP calculations. If strict compatibility is required to the versions previously available at the univie server, one can also download the versions "VASP release PAW POTCAR files: LDA & PBE, 5.2 & 5.4  (original univie release version)".
In the following, we will present the available PAW potentials. All distributed potentials have been tested using standard DFT-"benchmark" runs; see the ''data_base'' file in the released tar files. We strongly recommend using the [[POTCAR]]-files version 5.4 that is available as a download on the VASP Portal. The currently distributed [[POTCAR]] files of version 5.4 possess a unique SHA hash. The [[POTCAR]]-files version 5.2 is also quite popular and has been used in the [https://wiki.materialsproject.org/Pseudopotentials_Choice Materials Project]. Differences between version 5.4 and 5.2 are usually small and limited to few elements/POTCAR files. Each [[POTCAR]] file of version 5.2 that is presently available on the VASP Portal also possesses a unique SHA hash, and they have been slightly edited in the text part of the headers, which is irrelevant to VASP calculations. If strict compatibility is required to the versions previously available at the univie server, one can also download the versions "VASP release PAW POTCAR files: LDA & PBE, 5.2 & 5.4  (original univie release version)".
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=== d elements ===
=== d elements ===
The same applies to <math>d</math> elements as for the alkali and earth-alkali metals: the semi-core <math>p</math> states and possibly the semi-core <math>s</math> states should be treated as valence states. In most cases, however, reliable results can be obtained even if the semi-core states are kept frozen. As a rule of thumb the <math>p<math> states should be treated as valence states, if their eigenenergy <math>\epsilon</math> lies above 3 Ry.
The same applies to <math>d</math> elements as for the alkali and earth-alkali metals: the semi-core <math>p</math> states and possibly the semi-core <math>s</math> states should be treated as valence states. In most cases, however, reliable results can be obtained even if the semi-core states are kept frozen. As a rule of thumb the <math>p</math> states should be treated as valence states, if their eigenenergy <math>\epsilon</math> lies above 3 Ry.


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Revision as of 02:38, 9 August 2021

Projector augmented wave (PAW) potentials are available for all elements in the periodic table from the VASP Portal. These are pseudopotentials for the PAW method and are stored in POTCAR files. The distributed PAW potentials have been generated by G. Kresse following the recipes discussed in [1], whereas the PAW method has been first suggested and used by Peter Blöchl [2]. Therefore, if you use any of the supplied PAW potentials, you should include these two references.

Except for the 1st-row elements, all PAW potentials are designed to work reliably and accurately at an energy cutoff of roughly 250 eV. This is a key aspect of making the calculation computationally cheap. The default energy cutoff is set by the ENMAX tag in the POTCAR file. Generally, the PAW potentials are more accurate than ultra-soft pseudopotentials (US-PP). There are two reasons for this: First, the radial cutoffs (core radii) are smaller than the radii used for US-PP. Second, the PAW potentials reconstruct the exact valence wavefunction with all nodes in the core region. Since the core radii of the PAW potentials are smaller, the required energy cutoffs and basis sets are also larger. If such high precision is not required, the older US-PP can be used in principle, but it is discouraged. This is because the energy cutoffs have not changed appreciably for C, N, and O. Thus, the increase in the basis-set size will usually be small so that calculations for compounds that include any of these elements are not more expensive with PAW than with US-PP.

For some elements several PAW versions exist. The standard version has no extension. The extension _h implies that the potential is harder than the standard potential and hence requires a greater energy cutoff. The extension _s means that the potential is softer than the standard version. The extensions _pv and _sv imply that the and semi-core states are treated as valence states (i.e. for V_pv the states are treated as valence states, and for V_sv the and states are treated as valence states). PAW files with an extension _d, treat the semi core states as valence states (for Ga_d the states are treated as valence states).

The valence configuration underlying each PAW potential can be inferred from the ZVAL tag and the table written below Atomic configuration in the POTCAR file. The table lists first the core states and then the valence states. Hence, the final rows those occupancies add up to ZVAL comprise the valence configuration. Note that this can differ from the ground-state configuration in vacuum and that the rows are not ordered by energy. For instance, for Gd_3 strongly localized, semi-core electrons are treated as core states despite being higher in energy than other valence states.

In the following, we will present the available PAW potentials. All distributed potentials have been tested using standard DFT-"benchmark" runs; see the data_base file in the released tar files. We strongly recommend using the POTCAR-files version 5.4 that is available as a download on the VASP Portal. The currently distributed POTCAR files of version 5.4 possess a unique SHA hash. The POTCAR-files version 5.2 is also quite popular and has been used in the Materials Project. Differences between version 5.4 and 5.2 are usually small and limited to few elements/POTCAR files. Each POTCAR file of version 5.2 that is presently available on the VASP Portal also possesses a unique SHA hash, and they have been slightly edited in the text part of the headers, which is irrelevant to VASP calculations. If strict compatibility is required to the versions previously available at the univie server, one can also download the versions "VASP release PAW POTCAR files: LDA & PBE, 5.2 & 5.4 (original univie release version)".

Below, recommended potentials are reported in boldface.

All reported potentials are for PBE calculations. Therefore, the reported energy cutoffs might differ slightly for LDA potentials and different releases.

Recommended potentials for DFT calculations

The following table lists the PAW potentials for VASP.

Important Note: If dimers with short bonds are present in the compound (O2, CO, N2, F2, P2, S2, Cl2), we recommend to use the _h potentials. Specifically, C_h, O_h, N_h, F_h, P_h, S_h, Cl_h. Note that the listed default energy cutoffs might slightly change between different releases as noted above.

In version 5.4, W_sv has replaced the potential W_pv, and the At_d POTCAR file is no longer available because the potential leads to fairly large errors in the lattice constants.

default cutoff ENMAX (eV) valency
H 250 1
H_AE 1000 1
H_h 700 1
H_s 200 1
He 479 2
Li 140 1
Li_sv 499 3
Be 248 2
Be_sv 309 4
B 319 3
B_h 700 3
B_s 269 3
C 400 4
C_h 700 4
C_s 274 4
N 400 5
N_h 700 5
N_s 280 5
O 400 6
O_h 700 6
O_s 283 6
F 400 7
F_h 773 7
F_s 290 7
Ne 344 8
Na 102 1
Na_pv 260 7
Na_sv 646 9
Mg 200 2
Mg_pv 404 8
Mg_sv 495 10
Al 240 3
Si 245 4
P 255 5
P_h 390 5
S 259 6
S_h 402 6
Cl 262 7
Cl_h 409 7
Ar 266 8
K_pv 117 7
K_sv 259 9
Ca_pv 120 8
Ca_sv 267 10
Sc 155 3
Sc_sv 223 11
Ti 178 4
Ti_pv 222 10
Ti_sv 275 12
V 193 5
V_pv 264 11
V_sv 264 13
Cr 227 6
Cr_pv 266 12
Cr_sv 395 14
Mn 270 7
Mn_pv 270 13
Mn_sv 387 15
Fe 268 8
Fe_pv 293 14
Fe_sv 391 16
Co 268 9
Co_pv 271 15
Co_sv 390 17
Ni 270 10
Ni_pv 368 16
Cu 295 11
Cu_pv 369 17
Zn 277 12
Ga 135 3
Ga_d 283 13
Ga_h 405 13
Ge 174 4
Ge_d 310 14
Ge_h 410 14
As 209 5
As_d 289 15
Se 212 6
Br 216 7
Kr 185 8
Rb_pv 122 7
Rb_sv 220 9
Sr_sv 229 10
Y_sv 203 11
Zr_sv 230 12
Nb_pv 209 11
Nb_sv 293 13
Mo 225 6
Mo_pv 225 12
Mo_sv 243 14
Tc 229 7
Tc_pv 264 13
Tc_sv 319 15
Ru 213 8
Ru_pv 240 14
Ru_sv 319 16
Rh 229 9
Rh_pv 247 15
Pd 251 10
Pd_pv 251 16
Ag 250 11
Ag_pv 298 17
Cd 274 12
In 96 3
In_d 239 13
Sn 103 4
Sn_d 241 14
Sb 172 5
Te 175 6
I 176 7
Xe 153 8
Cs_sv 220 9
Ba_sv 187 10
La 219 11
La_s 137 9
Ce 273 12
Ce_h 300 12
Ce_3 177 11
Pr 273 13
Pr_3 182 11
Nd 253 14
Nd_3 183 11
Pm 259 15
Pm_3 177 11
Sm 258 16
Sm_3 177 11
Eu 250 17
Eu_2 99 8
Eu_3 129 9
Gd 256 18
Gd_3 154 9
Tb 265 19
Tb_3 156 9
Dy 255 20
Dy_3 156 9
Ho 257 21
Ho_3 154 9
Er_2 120 8
Er_3 155 9
Er 298 22
Tm 257 23
Tm_3 149 9
Yb 253 24
Yb_2 113 8
Lu 256 25
Lu_3 155 9
Hf 220 4
Hf_pv 220 10
Hf_sv 237 12
Ta 224 5
Ta_pv 224 11
W 223 6
W_sv 223 14
Re 226 7
Re_pv 226 13
Os 228 8
Os_pv 228 14
Ir 211 9
Pt 230 10
Pt_pv 295 16
Au 230 11
Hg 233 12
Tl 90 3
Tl_d 237 13
Pb 98 4
Pb_d 238 14
Bi 105 5
Bi_d 243 15
Po 160 6
Po_d 265 16
At 161 7
Rn 151 8
Fr_sv 215 9
Ra_sv 237 10
Ac 172 11
Th 247 12
Th_s 169 10
Pa 252 13
Pa_s 193 11
U 253 14
U_s 209 14
Np 254 15
Np_s 208 15
Pu 254 16
Pu_s 208 16
Am 256 17
Cm 258 18

Hydrogen-like potentials are supplied for a valency between 0.25 and 1.75, as listed in the table below. Further potentials might become available, and the list is not always up to date. Mind that the POTCAR files restrict the number of digits for the valency (typically 2, at most 3 digits). That is, using three H.33 potentials does not yield 0.99 electrons and not 1.00 electron. This can cause hole- or electron-like states that are undesirable. The solution is to slightly adjust the NELECT tag in the INCAR file.

Element (and appendix) default cutoff ENMAX (eV) valency
H .25 250 0.2500
H .33 250 0.3300
H .42 250 0.4200
H .5 250 0.5000
H .58 250 0.5800
H .66 250 0.6600
H .75 250 0.7500
H 1.25 250 1.2500
H 1.33 250 1.3300
H 1.5 250 1.5000
H 1.66 250 1.6600
H 1.75 250 1.7500

Recommended potentials for GW/RPA calculations

The available GW potentials are listed in the table below. For DFT calculations, the GW potentials yield virtually identical results as the PAW potentials recommended for DFT calculations above. That is, one can use the GW potentials instead of the potentials discussed above for DFT calculations without deteriorating the results. In fact, we have evidence from comparison with all-electron calculations that the GW potentials are slightly superior even for DFT calculations. They are certainly superior for excited-state properties, GW calculations, random phase approximation (RPA) calculations, and in general for any explicitly correlated wave function calculation (MP2, coupled-cluster).

In general, the GW potentials yield much better scattering properties at high energies well above the Fermi level, i.e., typically up to 10-20 Ry above the vacuum level.

Important Note: If dimers with short bonds are present in the compound (O2, CO, N2, F2, P2, S2, Cl2), we recommend to use the _h potentials. Specifically, C_GW_h, O_GW_h, N_GW_h, F_GW_h.

Element (and appendix) default cutoff ENMAX (eV) valency
H_GW 300 1
H_h_GW 700 1
He_GW 405 2
Li_sv_GW 434 3
Li_GW 112 1
Li_AE_GW 434 3
Be_sv_GW 537 4
Be_GW 248 2
B_GW 319 3
C_GW 414 4
C_GW_new 414 4
C_h_GW 741 4
N_GW 421 5
N_GW_new 421 5
N_h_GW 755 5
N_s_GW 313 5
O_GW 415 6
O_GW_new 434 6
O_h_GW 765 6
O_s_GW 335 6
F_GW 488 7
F_GW_new 488 7
F_h_GW 848 7
Ne_GW 432 8
Ne_s_GW 318 8
Na_sv_GW 372 9
Mg_sv_GW 430 10
Mg_GW 126 2
Mg_pv_GW 404 8
Al_GW 240 3
Al_sv_GW 411 11
Si_GW 245 4
Si_GW_new 245 4
Si_sv_GW 548 12
P_GW 255 5
S_GW 259 6
Cl_GW 262 7
Ar_GW 290 8
K_sv_GW 249 9
Ca_sv_GW 281 10
Sc_sv_GW 378 11
Ti_sv_GW 383 12
V_sv_GW 382 13
Cr_sv_GW 384 14
Mn_sv_GW 384 15
Mn_GW 278 7
Fe_sv_GW 387 16
Fe_GW 321 8
Co_sv_GW 387 17
Co_GW 323 9
Ni_sv_GW 389 18
Ni_GW 357 10
Cu_sv_GW 467 19
Cu_GW 417 11
Zn_sv_GW 401 20
Zn_GW 328 12
Ga_d_GW 404 13
Ga_GW 135 3
Ga_sv_GW 404 21
Ge_d_GW 375 14
Ge_sv_GW 410 22
Ge_GW 174 4
As_GW 209 5
As_sv_GW 415 23
Se_GW 212 6
Se_sv_GW 469 24
Br_GW 216 7
Br_sv_GW 475 25
Kr_GW 252 8
Rb_sv_GW 221 9
Sr_sv_GW 225 10
Y_sv_GW 339 11
Zr_sv_GW 346 12
Nb_sv_GW 353 13
Mo_sv_GW 344 14
Tc_sv_GW 351 15
Ru_sv_GW 348 16
Rh_sv_GW 351 17
Rh_GW 247 9
Pd_sv_GW 356 18
Pd_GW 251 10
Ag_sv_GW 354 19
Ag_GW 250 11
Cd_sv_GW 361 20
Cd_GW 254 12
In_d_GW 279 13
In_sv_GW 366 21
Sn_d_GW 260 14
Sn_sv_GW 368 22
Sb_d_GW 263 15
Sb_sv_GW 372 23
Sb_GW 172 5
Te_GW 175 6
Te_sv_GW 376 24
I_GW 176 7
I_sv_GW 381 25
Xe_GW 180 8
Xe_sv_GW 400 26
Cs_sv_GW 198 9
Ba_sv_GW 238 10
La_GW 313 11
Ce_GW 305 12
Hf_sv_GW 309 12
Ta_sv_GW 286 13
W_sv_GW 317 14
Re_sv_GW 317 15
Os_sv_GW 320 16
Ir_sv_GW 320 17
Pt_sv_GW 324 18
Pt_GW 249 10
Au_sv_GW 306 19
Au_GW 248 11
Hg_sv_GW 312 20
Tl_d_GW 237 15
Tl_sv_GW 316 21
Pb_d_GW 238 16
Pb_sv_GW 317 22
Bi_d_GW 261 17
Bi_GW 147 5
Bi_sv_GW 323 23
Po_d_GW 267 18
Po_sv_GW 326 24
At_d_GW 266 17
At_sv_GW 328 25
Rn_d_GW 268 18
Rn_sv_GW 331 26

The C_GW_new, N_GW_new, O_GW_new, and F_GW_new POTCAR files, use the f-pseudopotential as local potential and possess d-projectors. In contrast, the C_GW, N_GW, O_GW, and F_GW POTCAR files use the d-pseudopotential as local potential and possess no d-projectors. Calculations usually converge faster with respect to the energy cutoff ENMAX using the C_GW, N_GW, O_GW, and G_GW potentials. Whether the new potentials possess a precision advantage over the old potentials is not entirely clear. In theory, they should be more precise for correlated wavefunction calculations. However, in practice, the improvements seem modest and often do not justify the greater computational load.

Further recommendations regarding PAW potentials

In the following, we further explain the potentials for element groups.

1st row elements

Element (and appendix) default cutoff ENMAX (eV)
B 319 3
B_h 700 3
B_s 269 3
C 400 4
C_h 700 4
C_s 274 4
N 400 5
N_h 700 5
N_s 280 5
O 400 6
O_h 700 6
O_s 283 6
F 400 7
F_h 773 7
F_s 290 7
Ne 344 8

For the 1st row elements, three PAW versions exist. For most purposes, the standard version of PAW potentials is most appropriate. They yield reliable results for energy cutoffs between 325 and 400 eV, where 370-400 eV are required to predict vibrational properties accurately. Binding geometries and energy differences are already well reproduced at 325 eV. The typical bond-length errors for first row dimers (N2, CO, O2) are about 1% compared to more accurate DFT calculations. The hard pseudopotentials _h give results that are essentially identical to the best DFT calculations presently available (FLAPW, or Gaussian with very large basis sets). The soft potentials are optimized to work around 250-280 eV. They yield reliable description for most oxides, such as VxOy, TiO2, CeO2, but fail to describe some structural details in zeolites, i.e., cell parameters, and volume.

For Hartree-Fock (HF) and hybrid functional calculations, we strictly recommend using the standard, standard GW, or hard potentials. For instance, the O_s potential can cause unacceptably large errors even in transition metal oxides. Generally, the soft potentials are less transferable from one exchange-correlation functional to another and often fail when the exact exchange needs to be calculated.

Alkali and alkali-earth elements (simple metals)

For Li (and Be), a standard potential and a potential that treats the shell as valence states are available (Li_sv, Be_sv). One should use the _sv potentials for many applications since their transferability is much higher than the standard potentials.

For the other alkali and alkali-earth elements, the semi-core and states should be treated as valence states as well. For lighter elements (Na-Ca) it is usually sufficient to treat the and states as valence states (_pv), respectively. For Rb-Sr the , , and , states, respectively, must be treated as valence states (_sv). The standard potentials are listed below. The default energy cutoffs are specified as well but might vary from one release to the other.

Element (and appendix) default cutoff ENMAX (eV) valency
H 250 1
H_h 700 1
Li 140 1
Li_sv 499 3
Na 102 1
Na_pv 260 7
Na_sv 646 9
K_pv 117 7
K_sv 259 9
Rb_pv 122 7
Rb_sv 220 9
Cs_sv 220 9
Be 248 2
Be_sv 309 4
Mg 200 2
Mg_pv 404 8
Mg_sv 495 10
Ca_pv 120 8
Ca_sv 267 10
Sr_sv 229 10
Ba_sv 187 10


Contrary to the common belief, these elements are exceedingly difficult to pseudize in particular in combination with strongly electronegative elements (F) errors can be larger than usual. The present potentials are very precise and should offer a very reliable description. For X_pv potentials the semi-core states are treated as valence, e.g., in Na and Mg, in K and Ca, etc. For X_sv potentials, the semi-core states are treated as valence, e.g., in Li and Be, in Na, etc.

d elements

The same applies to elements as for the alkali and earth-alkali metals: the semi-core states and possibly the semi-core states should be treated as valence states. In most cases, however, reliable results can be obtained even if the semi-core states are kept frozen. As a rule of thumb the states should be treated as valence states, if their eigenenergy lies above 3 Ry.

Element (and appendix) default cutoff ENMAX (eV) valency
Sc 155 3
Sc_sv 223 11
Fe 268 8
Fe_pv 293 14
Fe_sv 391 16
Y_sv 203 11
Ru 213 8
Ru_pv 240 14
Ru_sv 319 16
Os 228 8
Os_pv 228 14
Ti 178 4
Ti_pv 222 10
Ti_sv 275 12
Co 268 9
Co_pv 271 15
Co_sv 390 17
Zr_sv 230 12
Rh 229 9
Rh_pv 247 15
Hf 220 4
Hf_pv 220 10
Ir 211 9
V 193 5
V_pv 264 11
V_sv 264 13
Ni 270 10
Ni_pv 368 16
Nb_pv 209 11
Nb_sv 293 13
Pd 251 10
Pd_pv 251 16
Ta 224 5
Ta_pv 224 11
Pt 230 10
Pt_pv 295 16
Cr 227 6
Cr_pv 266 12
Cr_sv 395 14
Cu 295 11
Cu_pv 369 17
Mo 225 6
Mo_pv 225 12
Mo_sv 243 14
Ag 250 11
Ag_pv 298 17
W 223 6
W_sv 223 14
Au 230 11
Mn 270 7
Mn_pv 270 13
Mn_sv 387 15
Zn 277 12
Tc 229 7
Tc_pv 264 13
Tc_sv 319 15
Cd 274 12
Re 226 7
Re_pv 226 13
Hg 233 12


For X_pv potentials, the semi core states are treated as valence, whereas for X_sv pseudopotentials, the semi-core states are treated as valence. X_pv potentials are required for early transition metals, but one can freeze the semi-core states for late transition metals; particularly for noble metals.

When to switch from X_pv potentials to the X potentials depends on the required accuracy and the row for the elements, even the Ti, V, and Cr potentials give reasonable results but should be used with uttermost care. elements are most problematic, and I advice to use the X_pv potentials up to Tc_pv. For elements the states are rather strongly localized (below 3 Ry), since the shell becomes filled. One can use the standard potentials starting from Hf, but we recommend performing test calculations. For some elements, X_sv potential are available (e.g. Nb_sv, Mo_sv, Hf_sv). These potentials usually have very similar energy cutoffs as the _pv potentials and can also be used. For HF-type and hybrid functional calculations, we strongly recommend using the _sv and _pv potentials whenever possible.

p-elements including first row

Element (and appendix) default cutoff ENMAX (eV) valency
B_h 700 3
B 319 3
B_s 269 3
Al 240 3
Ga 135 3
Ga_d 283 13
Ga_h 405 13
In 96 3
In_d 239 13
Tl 90 3
Tl_d 237 13
C_h 700 4
C 400 4
C_s 274 4
Si 245 4
Ge 174 4
Ge_d 310 14
Ge_h 410 14
Sn 103 4
Sn_d 241 14
Pb 98 4
Pb_d 238 14
N_h 700 5
N 400 5
N_s 280 5
P 255 5
P_h 390 5
As 209 5
As_d 289 15
Sb 172 5
Bi 105 5
Bi_d 243 15
O_h 700 6
O 400 6
O_s 283 6
S 259 6
S_h 402 6
Se 212 6
Te 175 6
Po 160 6
Po_d 265 16
F_h 773 7
F 400 7
F_s 290 7
Cl 262 7
Cl_h 409 7
Br 216 7
I 176 7
At 161 7
Ne 344 8
Ar 266 8
Kr 185 8
Xe 153 8
Rn 152 8

For Ga, Ge, In, Sn, Tl-At, the lower-lying states should be treated as valence states (_d potential). For these elements, alternative potentials that treat the states as core states are also available but should be used with great care.

f elements

Due to self-interaction errors, electrons are not handled well by the presently available density functionals. In particular, partially filled states are often incorrectly described. For instance, all states are pinned at the Fermi-level, leading to large overbinding for Pr-Eu and Tb-Yb. The errors are largest at quarter, and three-quarter filling, e.g., Gd is handled reasonably well since 7 electrons occupy the majority shell. These errors are DFT and not VASP related. Particularly problematic is the description of the transition from an itinerant (band-like) behavior observed at the beginning of each period to localized states towards the end of the period. For the elements, this transition occurs already in La and Ce, whereas the transition sets in for Pu and Am for the elements. A routine way to cope with the inabilities of present DFT functionals to describe the localized electrons is to place the electrons in the core. Such potentials are available and described below; however, they are expected to fail to describe magnetic properties arising orbitals. Furthermore, PAW potentials in which the states are treated as valence states are available, but these potentials are expected to fail to describe electronic properties when electrons are localized. In this case, one might treat electronic correlation effects more carefully, e.g., by employing hybrid functionals or introduce on-site Coulomb interaction.

Element (and appendix) default cutoff ENMAX (eV) valency
La 219 11
Ac 172 11
Ce 273 12
Tb 265 19
Th 247 12
Th_s 169 10
Pr 273 13
Dy 255 20
Pa 252 13
Pa_s 193 11
Nd 253 14
Ho 257 21
U 253 14
U_s 209 14
Pm 259 15
Er 298 22
Np 254 15
Np_s 208 15
Sm 258 16
Tm 257 23
Pu 254 16
Pu_s 208 16
Eu 250 17
Yb 253 24
Am 256 17
Gd 256 18
Lu 256 25

For some elements, soft versions (_s) are available as well. The semi-core states are always treated as valence states, whereas the semi-core states are treated as valence states only in the standard potentials. For most applications (oxides, sulfides), the standard version should be used since the soft versions might result in ghost-states close to the Fermi-level (e.g., Ce_s in ceria). For calculations on intermetallic compounds, the soft versions are, however, expected to be sufficiently accurate.

In addition, special GGA potentials are supplied for Ce-Lu, in which electrons are kept frozen in the core, which is an attempt to treat the localized nature of electrons. The number of f electrons in the core equals the total number of valence electrons minus the formal valency. For instance: According to the periodic table, Sm has a total of 8 valence electrons, i.e., 6 electrons and 2 electrons. In most compounds, Sm adopts a valency of 3; hence 5 electrons are placed in the core when the pseudopotential is generated. The corresponding potential can be found in the directory Sm_3. The formal valency n is indicted by _n, where n is either 3 or 2. Ce_3 is, for instance, a Ce potential for trivalent Ce (for tetravalent Ce, the standard potential should be used).

Element (and appendix) default cutoff ENMAX (eV) valency
Ce_3 177 11
Tb_3 156 9
Pr_3 182 11
Dy_3 156 9
Nd_3 184 11
Ho_3 154 9
Pm_3 177 11
Er_3 155 9
Er_2 120 8
Sm_3 177 11
Tm_3 149 9
Eu_3 129 9
Eu_2 99 8
Yb_3 188 9
Yb_2 113 8
Gd_3 154 9
Lu_3 155 9

References