#acl +All:read apw185:read,write,delete Known:read All: <> [[AJMPublic/potentials/methane|Back to Methane Potentials page]] = Methane: Isotropic model = Summary: 1. ISA charge model for electrostatics. No damping. 1. L1, isotropic undamped polarization model scaled by prefactor to fit better for low interaction energies in the water-methane dimer, see water-methane model*. 1. $C_{6}$, isotropic damped dispersion model. 1. Isotropic exchange-repulsion terms only. Units: Atomic Units == Citations == * A. J. Misquitta & A. J. Stone, //Ab initio atom–atom potentials using CamCASP: Theory// == Geometry and charges == Source: BS-ISA, A+DF $\zeta=0.1$ aug-cc-pVTZ main basis with aQZ/set2 aux basis. PBE0/AC. CamCASP 5.8. [[attachment:CH4-ISA.mom]] {{{ ! Based on DF-type : ISA C 0.00000000 0.00000000 0.00000000 Type C Rank 0 -0.413530 H1 0.00000000 2.07703578 0.00000000 Type H Rank 0 0.103598 H2 1.69589261 -0.69234525 0.97912406 Type H Rank 0 0.103383 H3 -1.69589261 -0.69234525 0.97912406 Type H Rank 0 0.103383 H4 0.00000000 -0.69234525 -1.95824810 Type H Rank 0 0.103166 }}} == Polarizability == Source: Averaged terms taken from WSM L3,aniso; then multiplied by 1.08735 to better fit low-energy water-methane dimers, see *. Main basis: d-aug-cc-pVTZ; Aux-basis: aug-cc-pVQZ. PBE0/AC with ALDA+CHF kernel. CamCASP 5.8. [[attachment:CH4-averaged-scaled.pol]] {{{ # Static polarizabilities C C 0.000 0.0000000 0.0000000 0.0000000 0.000 6.31667820135 0.0000000 0.0000000 0.000 0.0000000 6.31667820135 0.0000000 0.000 0.0000000 0.0000000 6.31667820135 H1 H1 0.000 0.0000000 0.0000000 0.0000000 0.000 3.19768616524 0.0000000 0.0000000 0.000 0.0000000 3.19768616524 0.0000000 0.000 0.0000000 0.0000000 3.19768616524 H2 H2 0.000 0.0000000 0.0000000 0.0000000 0.000 3.19768616524 0.0000000 0.0000000 0.000 0.0000000 3.19768616524 0.0000000 0.000 0.0000000 0.0000000 3.19768616524 H3 H3 0.000 0.0000000 0.0000000 0.0000000 0.000 3.19768616524 0.0000000 0.0000000 0.000 0.0000000 3.19768616524 0.0000000 0.000 0.0000000 0.0000000 3.19768616524 H4 H4 0.000 0.0000000 0.0000000 0.0000000 0.000 3.19768616524 0.0000000 0.0000000 0.000 0.0000000 3.19768616524 0.0000000 0.000 0.0000000 0.0000000 3.19768616524 }}} == Potential & Damping == Coefficients fitted using Orient. Tang-Toennies damping. Single dispersion damping coefficient, no induction damping. [[attachment:CH4-iso-scaled.pot]] {{{ C C rho alpha Induction DAMPING OFF Dispersion damping Factor 1.93 C C rho alpha C6 00 00 0 6.227951 2.128586 22.07923 END C H rho alpha C6 00 00 0 4.681533 1.828324 10.09522 END H H rho alpha C6 00 00 0 4.371667 1.535312 4.87260 END }}} == Sample Orient command file == You will need the above files present in the directory as they are '''included''' into this Orient file. Orient version: 4.7/4.8 [[attachment:CH4_2-iso-scaled.ornt]] {{{ UNITS BOHR Parameters Sites 100 polarizable 100 S-functions 50000 Alphas 50000 Parameter-sets 50000 Pairs 100000 Molecules 10 End Types C Z 6 H Z 1 End Variables Rx 10.0 B Ry 0.0 B Rz 0.0 B alpha 0.0 D Nx 0.0 Ny 0.0 Nz 1.0 Index 0 End Molecule CH4_A at 0 0 0 rotated by 0 about 0 0 1 #include CH4-ISA.mom End Polarizabilities for CH4_A Read rank 1 #include CH4-averaged-scaled.pol End Limit rank 1 for C H1 H2 H3 H4 End Molecule CH4_B at Rx Ry Rz rotated by alpha about Nx Ny Nz #include CH4-ISA.mom End Polarizabilities for CH4_B Read rank 1 #include CH4-averaged-scaled.pol End Limit rank 1 for C H1 H2 H3 H4 End Pairs #include ./CH4-iso-scaled.pot End Units Bohr kJ/mol Switch Induce On Iterate On Options Induction Iterations 100 Convergence 1e-12 End Units Bohr kJ/mol Comment "Energy calculation" Energy Table Format e15.7 Print es er ind disp total Variables Index Rx Ry Rz alpha Nx Ny Nz 2 0.00 -4.20 0.00 180 1.000 0.000 0.000 3 0.00 -4.90 0.00 180 1.000 0.000 0.000 4 0.00 -5.60 0.00 180 1.000 0.000 0.000 5 0.00 -6.30 0.00 180 1.000 0.000 0.000 6 0.00 -6.65 0.00 180 1.000 0.000 0.000 7 0.00 -7.00 0.00 180 1.000 0.000 0.000 8 0.00 -7.35 0.00 180 1.000 0.000 0.000 9 0.00 -7.70 0.00 180 1.000 0.000 0.000 10 0.00 -8.40 0.00 180 1.000 0.000 0.000 11 0.00 -9.10 0.00 180 1.000 0.000 0.000 12 0.00 -9.80 0.00 180 1.000 0.000 0.000 End Finish }}} Output should end with [[attachment:end of output]] {{{ Rx Ry Rz alpha Nx Ny Nz Index es er ind disp total }}}