move two more parameter arrays to header and make them static constexpr

src/EXTRA-PAIR/d3_parameters.h

@@ -20,6 +20,51 @@
 #ifndef LMP_D3_PARAMETERS_H
 #define LMP_D3_PARAMETERS_H
 
+// clang-format off
+
+/* scale r4/r2 values of the atoms by sqrt(Z)
+   * sqrt is also globally close to optimum
+   * together with the factor 1/2 this yield reasonable
+   * c8 for he, ne and ar. for larger Z, C8 becomes too large
+   * which effectively mimics higher R^n terms neglected due
+   * to stability reasons.
+   * r2r4 =sqrt(0.5*r2r4(i)*ddouble(i)**0.5 ) with i=elementnumber
+   * the large number of digits is just to keep the results consistent
+   * with older versions. They should not imply any higher accuracy than
+   * the old values */
+
+static constexpr double r2r4_ref[NUM_ELEMENTS + 1] = {
+    0,           2.00734898,  1.56637132,  5.01986934,  3.85379032,  3.64446594,  3.10492822,
+    2.71175247,  2.59361680,  2.38825250,  2.21522516,  6.58585536,  5.46295967,  5.65216669,
+    4.88284902,  4.29727576,  4.04108902,  3.72932356,  3.44677275,  7.97762753,  7.07623947,
+    6.60844053,  6.28791364,  6.07728703,  5.54643096,  5.80491167,  5.58415602,  5.41374528,
+    5.28497229,  5.22592821,  5.09817141,  6.12149689,  5.54083734,  5.06696878,  4.87005108,
+    4.59089647,  4.31176304,  9.55461698,  8.67396077,  7.97210197,  7.43439917,  6.58711862,
+    6.19536215,  6.01517290,  5.81623410,  5.65710424,  5.52640661,  5.44263305,  5.58285373,
+    7.02081898,  6.46815523,  5.98089120,  5.81686657,  5.53321815,  5.25477007, 11.02204549,
+   10.15679528,  9.35167836,  9.06926079,  8.97241155,  8.90092807,  8.85984840,  8.81736827,
+    8.79317710,  7.89969626,  8.80588454,  8.42439218,  8.54289262,  8.47583370,  8.45090888,
+    8.47339339,  7.83525634,  8.20702843,  7.70559063,  7.32755997,  7.03887381,  6.68978720,
+    6.05450052,  5.88752022,  5.70661499,  5.78450695,  7.79780729,  7.26443867,  6.78151984,
+    6.67883169,  6.39024318,  6.09527958, 11.79156076, 11.10997644,  9.51377795,  8.67197068,
+    8.77140725,  8.65402716,  8.53923501,  8.85024712};    // atomic <r^2>/<r^4> values
+
+static constexpr double rcov_ref[NUM_ELEMENTS + 1] = {
+    0,           0.80628308,  1.15903197,  3.02356173,  2.36845659,  1.94011865,  1.88972601,
+    1.78894056,  1.58736983,  1.61256616,  1.68815527,  3.52748848,  3.14954334,  2.84718717,
+    2.62041997,  2.77159820,  2.57002732,  2.49443835,  2.41884923,  4.43455700,  3.88023730,
+    3.35111422,  3.07395437,  3.04875805,  2.77159820,  2.69600923,  2.62041997,  2.51963467,
+    2.49443835,  2.54483100,  2.74640188,  2.82199085,  2.74640188,  2.89757982,  2.77159820,
+    2.87238349,  2.94797246,  4.76210950,  4.20778980,  3.70386304,  3.50229216,  3.32591790,
+    3.12434702,  2.89757982,  2.84718717,  2.84718717,  2.72120556,  2.89757982,  3.09915070,
+    3.22513231,  3.17473967,  3.17473967,  3.09915070,  3.32591790,  3.30072128,  5.26603625,
+    4.43455700,  4.08180818,  3.70386304,  3.98102289,  3.95582657,  3.93062995,  3.90543362,
+    3.80464833,  3.82984466,  3.80464833,  3.77945201,  3.75425569,  3.75425569,  3.72905937,
+    3.85504098,  3.67866672,  3.45189952,  3.30072128,  3.09915070,  2.97316878,  2.92277614,
+    2.79679452,  2.82199085,  2.84718717,  3.32591790,  3.27552496,  3.27552496,  3.42670319,
+    3.30072128,  3.47709584,  3.57788113,  5.06446567,  4.56053862,  4.20778980,  3.98102289,
+    3.82984466,  3.85504098,  3.88023730,  3.90543362};    // covalent radii
+
 static constexpr double r0ab_table[NUM_ELEMENTS][NUM_ELEMENTS] = {
     {2.18230000E+00, 1.85470000E+00, 2.90860000E+00, 2.35500000E+00, 2.51410000E+00, 2.44920000E+00,
      2.36670000E+00, 2.17680000E+00, 2.06460000E+00, 1.98920000E+00, 2.98980000E+00, 2.51290000E+00,