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Core-Shell
Interactions The additional parameters are read from the species record. There is no range record nor an ENDS record for the HARM potential. The record is used to input parameters which describe the self energy of the shell. In the conventional shell model, this is just the dipole energy of the separated core and shell. In the ellipsoidal shell model it includes terms for the self energy due to breathing and distortion of the shell. The analytic form of the dipole part of the potential is
The and operands are optional. If omitted, their values are set equal to zero. If the ellipsoidal shell model is being used, the and parameters must be included and set equal to zero if not used. Either two or four additional parameters are required on the species record. These parameters are, in order, two ellipsoidal force constants and two optional anharmonic parameters. The form of the ellipsoid self energy is.
Where The units of and are given below
is dimensionless. is a force constant for a pure ellipsoidal distortion and is a force constasnt for pure breathing distortion. If either of these distortions is not required then the force constant should be set equal to a large number. (A value of 1000.0 would be appropriate.) controls how anharmonic the potential is. The default value if the parameters are omitted is 4.0. The energy will diverge as approaches (from an initial infinite value) for pure ellipsoidal distortion or as approaches for pure breathing, again from an initial infinite value for no breathing. A value of 1.0 gives no anharmonicity. LABELA and LABELB on the species record must be the core and shell of the same ion.Printed outputHARMONIC CORE-SHELL INTERACTION BETWEEN SPECIES Labeli AND Labelj THIS HAS THE FORM V(R) = 1/2*K1*R**2 + 1/24*K2*R**4 + 1/720*K3*R**6 K1 = k1 K2 = k2 K3 = k3If the ions are ellipsoidal, the following is printed. THESE SPECIES ALSO HAVE AN ELLIPSOID FORCE CONSTANT KEL THE FORM OF THE ELLIPSOID ENERGY IS E = 1/2 * KEL1 * (H-G) / ( 1 - 4/9 * (H-G)/RCAT**2) + 1/2 * KEL2 * (H+2G) / (1 - 4/9 * (H+2G)/RCAT**2) H = H1**2 + H2**2 + H3**2 G = H1*H2 + H1*H3 + H2*H3 THE FORCE CONSTANTS ARE kel1 kel2 Error messagesERROR - A HARMONIC CORE-SHELL INTERACTION MUST BE BETWEEN THE CORE AND SHELL OF THE SAME ION
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Next: Job Steps In DMAREL - Short Range Potential Input: Three-Body Interactions Previous: Job Steps In DMAREL - Short Range Potential Input: Short Range Interactions Contents: Contents Page |