All calculations and data processing are performed with the same set of computational protocols referenced below:

- Molecular crystal CIF refinement
- Molecular crystal geometry optimization (initial geometry is usually the experimental one)

Datasets are composed and will be refined in future according to the following principles:

- All included materials have a well-defined 'main' polymorph known either experimentally (in most of the cases) or obtained by comprehensive computational search. Here "well defined" means that different accurate approaches (including experiment) converge to the same structure.
- All crystals are dynamically stable except for a few higher energy polymorphs either with small imaginary frequencies or important for some reason (e.g. structural prototypes). For crystals with large unit cell vibrational frequencies are not calculated.
- Majority of datasets are limited to elements of the first three periods. Some datasets involve elements of the 4th period, e.g. transition metals. Heavier elements are avoided.

All data are 7-zipped into one archive per method (see next Section) + experimental data + core data (the dataset itself). Below is more detailed information about each subset including list of systems in each subset as text files whose first line contains coma-separated list of entries. See description of notations at the end of this webpage. Because for isolated molecules much more complicated calculations can be performed in a basis of atomic orbitals, we have added single-molecule calculations below.

- Main polymorph of single-conformer molecules [ver.20230222, 67 molecules, table, figure, details]: acenes, oligothiophenes, PAHs, azaacenes, thienoacenes, imides, quinones, indigos, and other core systems including TCNQs, stilbene, TTF, C60
- [To be uploaded soon] Polymorphs
- [To be uploaded soon] Multi-conformer molecules with side chains + crystalline sidechains
- [Not too many, to be uploaded later] Polymers
- [Not too many, to be uploaded later] Metal-organics
- [In development] Impurities and intrinsic defects

- PBE-D3paw900
- PBE-D3paw900_MA (medium accuracy)
- PBE-D3paw600 (volume scan)
- R2SCAN-D3paw900
- R2SCAN-D3paw900_MA (medium accuracy)

Isolated molecules

The database is grouped in folders, each folder corresponding to a single polymorph encoded in the folder name as
`system_polymorph`

, where 'system' is the name of the material and 'polymorph' is the polymorph label,
e.g. 'cryst-b' for beta-polymorph, 'cryst-aH' for high-symmetry/temperature alpha-polymorph,
'cryst-x' for purely computational polymorph, 'cryst' is the main polymorph,
'cryst-MA' for medium-accuracy geometry (EDIFFG=1E-4), and so forth.
Each folder contains the following files:

`main.dat`

core data such as name of the molecule and PubChem CID`molec.xyz`

molecular geometry, topology, and formal atomic types based on nearest neighbors`polymoprh.xyz`

crystal geometry, number of molecules in unit cell, space group and its orbits if there are symmetry-inequivalent molecules`polymoprh_method.xyz`

geometry optimized/obtained by 'method' in XYZ-format (see method notations, 'exp' means experimental data)`polymoprh_method.cif`

CIF-version of geometry for visualization only (less complete that XYZ-file)`polymoprh_method.out`

single point calculation of energy with fine k-grid`polymoprh_method_sp.out`

single point calculation of energy with the same k-grid as in geometry optimization`polymoprh_method_freq.out`

calculation of vibrational modes at Gamma-point (due to large size these files are available per request)`polymoprh_method_freq.txt`

brief analysis of the above file`polymoprh_method_vs.pdf`

volume scan and equation of state parameters in graphical format`polymoprh_method_vs.txt`

volume scan and equation of state parameters in text format`molec_method.xyz`

geometry of an isolated molecule optimized by 'method' in XYZ-format`molec_method.out`

single point calculation of total energy of an isolated molecule`molec_method_esp.out`

atomic charges (ESP, CM5, Hirshfeld)`V1vsT.txt`

thermal expansion data`V1vsT.pdf`

thermal expansion plot

To minimize use of special symbols we denote Ao=Å, deg=degree (angle), iX=X^(-1), X/mol=X per molecule, dX=deviation of X in % except for angles.

`[a,b,c,alpha,beta,gamma]`

(Ao,deg) unit cell parameters`[dr,phi,dev]`

(mAo,deg,mAo) displacement, deflection, and RMS deviation of intramolecular geometry without hydrogens (molecules are superimposed by MolMod/Superimpose, the result is RMS-averaged over all symmetry-unique molecules)`al=alpha`

(ppm/K) thermal expansion coefficient`conf`

conformation or configuration`dbet`

(deg) absolute deviation of monoclinic angle`dHOMO,dLUMO`

(eV) energy gap between HOMO/LUMO and next HOMO/LUMO`dlen`

(%) deviation of length of translation vectors (three-dimensional vector)`dSh`

(%) deviation of shape of unit cell, the same as`dTv`

but with volume rescaled to unity`dTv`

(%) RMS deviation of translation vectors (Frobenius norm of the unit cell matrix divided by square root of the number of translation vectors) divided by cubic root of the unit cell volume (the compared unit cell is rotated to minimize this RMS deviation, the code is BasicTools/SuperimposeM)`Eb`

(eV/mol) binding energy`el`

list of chemical elements`EM,EM1`

(GPa) elastic matrix (elasticity tensor in Voigt notation) and its lowest eigenvalue`freq1`

(meV) lowest vibrational frequency`gap`

(eV) HOMO-LUMO gap`id=sys`

BMCOS system identifier, usually a common name of a molecule`K,GR,GV`

(GPa) bulk and shear moduli calculated from`EM`

by MolMod/exam_vas/PrintFreq [Sewell03]`K0,K0'`

(GPa,1) bulk modulus and its derivative calculated by Murnaghan equation of state fit, the code is MolMod/EOSfit`mult=m`

number of primitive cells in Bravais unit cell`na`

number of atoms in unit cell`na1,nas,nu=Z`

number of atoms in the smallest repeating unit, list of number of atoms in molecules from this unit, and number of such units`name`

IUPAC-consistent chemical name of a molecule`nb`

number of electronic bands (NBANDS)`nd`

number of data points`ng`

number of elements in`SG`

`nkp`

number of k-points`nm`

number of molecules in unit cell (usually Bravais unit cell)`no`

number of symmetry-unique molecules, i.e. number of orbits in`orbs`

`nopt`

number of geometry relaxation iterations`nscf`

number of SCF iterations`nstab=ns`

number of elements in point symmetry group (stabilizer) of molecules in crystal`orbs`

symmetry-generated orbits of molecules in unit cell as list of lists of molecule indexes`PG`

point group`pubchem`

PubChem identifier`SG`

symmetry group or space group if combined with`PG`

`T`

(K) temperature`td`

(days) wall-clock computing time in days`Up2=|G|,maxG`

(meV/Ao) RMS norm and maximum absolute force on atoms`V`

(Ao^3) unit cell volume`V0`

(Ao^3) volume per atom extrapolated to 0K`V1`

(Ao^3) volume per atom